D. B. Cooper

D. B. Cooper
A 1972 FBI composite drawing of D. B. Cooper
Other names	Dan Cooper
Occupation	Unknown
Known for	Hijacking a Boeing 727 on November 24, 1971, and parachuting from the plane mid-flight; has never been positively identified or captured.

Northwest Orient Airlines Flight 305

Hijacking
Date	November 24, 1971
Summary	Hijacking
Site	Between Portland, Oregon and Seattle, Washington, USA
Aircraft
Aircraft type	Boeing 727
Operator	Northwest Orient Airlines
Registration	N467US
Flight origin	Portland International Airport
Destination	Seattle-Tacoma International Airport
Passengers	36 plus hijacker
Crew	6
Fatalities	none known (hijacker's fate unknown)
Injuries	none known
Survivors	all 42 passengers and crew

D. B. Cooper is a media epithet popularly used to refer to an unidentified man who hijacked a Boeing 727 aircraft in the airspace between Portland, Oregon, and Seattle, Washington, on November 24, 1971, extorted $200,000 in ransom (equivalent to $1,500,000 in 2023), and parachuted to an uncertain fate. Despite an extensive manhunt and an ongoing FBI investigation, the perpetrator has never been located or positively identified. The case remains the only unsolved air piracy in American aviation history.

The suspect purchased his airline ticket using the alias Dan Cooper, but because of a news media miscommunication he became known in popular lore as "D. B. Cooper". Hundreds of leads have been pursued in the ensuing years, but no conclusive evidence has ever surfaced regarding Cooper's true identity or whereabouts. Numerous theories of widely varying plausibility have been proposed by experts, reporters, and amateur enthusiasts. The discovery of a small cache of ransom bills in 1980 triggered renewed interest but ultimately only deepened the mystery, and the great majority of the ransom remains unrecovered.

While FBI investigators have stated from the beginning that Cooper probably did not survive his risky jump, the agency maintains an active case file—which has grown to more than 60 volumes—and continues to solicit creative ideas and new leads from the public. "Maybe a hydrologist can use the latest technology to trace the $5,800 in ransom money found in 1980 to where Cooper landed upstream," suggested Special Agent Larry Carr, leader of the investigation team since 2006. "Or maybe someone just remembers that odd uncle."

Hijacking

The incident began mid-afternoon on Thanksgiving eve, November 24, 1971, at Portland International Airport in Portland, Oregon. A man carrying a black attaché case approached the flight counter of Northwest Orient Airlines. He identified himself as "Dan Cooper" and purchased a one-way ticket on Flight 305, a 30-minute trip to Seattle, Washington.

Cooper boarded the aircraft, a Boeing 727-100 (FAA registration N467US), and took seat 18C (18E by one account, 15D by another) in the rear of the passenger cabin. He lit a cigarette and ordered a bourbon and soda. Eyewitnesses on board recalled a man in his mid-forties, between 5 feet 10 inches (1.78 m) and 6 feet 0 inches (1.83 m) tall. He wore a black lightweight raincoat, loafers, a dark suit, a neatly pressed white collared shirt, a black necktie, and a mother of pearl tie pin.

FBI wanted poster of D. B. Cooper

Flight 305, approximately one-third full, took off on schedule at 2:50 pm, local time (PST). Cooper passed a note to Florence Schaffner, the flight attendant situated nearest to him in a jumpseat attached to the aft stair door. Schaffner, assuming the note contained a lonely businessman's phone number, dropped it unopened into her purse. Cooper leaned toward her and whispered, "Miss, you'd better look at that note. I have a bomb."

The note was printed in neat, all-capital letters with a felt pen. It read, approximately, "I have a bomb in my briefcase. I will use it if necessary. I want you to sit next to me. You are being hijacked." Schaffner did as requested, then quietly asked to see the bomb. Cooper cracked open his briefcase long enough for her to glimpse eight red cylinders ("four on top of four") attached to wires coated with red insulation, and a large cylindrical battery. After closing the briefcase, he dictated his demands: $200,000 in "negotiable American currency"; four parachutes (two primary and two reserve); and a fuel truck standing by in Seattle to refuel the aircraft upon arrival. Schaffner conveyed Cooper's instructions to the cockpit; when she returned, he was wearing dark sunglasses.

The pilot, William Scott, contacted Seattle-Tacoma Airport air traffic control, which in turn informed local and federal authorities. The 36 other passengers were informed that their arrival in Seattle would be delayed because of a "minor mechanical difficulty". Northwest Orient's president, Donald Nyrop, authorized payment of the ransom and ordered all employees to cooperate fully with the hijacker. The aircraft circled Puget Sound for approximately two hours to allow Seattle police and the FBI time to assemble Cooper's parachutes and ransom money, and to mobilize emergency personnel.

Schaffner recalled that Cooper appeared familiar with the local terrain; at one point he remarked, "Looks like Tacoma down there," as the aircraft flew above it. He also mentioned, correctly, that McChord Air Force Base was only a 20-minute drive from Seattle-Tacoma Airport. Schaffner described him as calm, polite, and well-spoken, not at all consistent with the stereotypes (enraged, hardened criminals or "take-me-to-Cuba" political dissidents) popularly associated with air piracy at the time. Tina Mucklow, another flight attendant, agreed. "He wasn't nervous," she told investigators. "He seemed rather nice. He was never cruel or nasty. He was thoughtful and calm all the time." He ordered a second bourbon and water, paid his drink tab (and insisted Schaffner keep the change), and offered to request meals for the flight crew during the stop in Seattle.

FBI agents assembled the ransom money from several Seattle-area banks—10,000 unmarked 20-dollar bills, many with serial numbers beginning with the letter "L" indicating issuance by the Federal Reserve Bank of San Francisco, most carrying a "Series 1969-C" designation—and made a microfilm photograph of each of them. Cooper rejected the military-issue parachutes initially offered by authorities, demanding instead civilian parachutes with manually operated ripcords. Seattle police obtained them from a local skydiving school.

Passengers released

At 5:24 pm Cooper was informed that his demands had been met, and at 5:39 pm the aircraft landed at Seattle-Tacoma Airport. Cooper instructed Scott to taxi the jet to an isolated, brightly lit section of the tarmac and extinguish lights in the cabin to deter police snipers. Northwest Orient's Seattle operations manager, Al Lee, approached the aircraft in street clothes (to avoid the possibility that Cooper might mistake his airline uniform for that of a police officer) and delivered the cash-filled knapsack and parachutes to Mucklow via the aft stairs. Once the delivery was completed Cooper permitted all passengers, Schaffner, and senior flight attendant Alice Hancock to leave the plane.

During refueling Cooper outlined his flight plan to the cockpit crew: a southeast course toward Mexico City at the minimum airspeed possible without stalling the aircraft—approximately 100 knots (190 km/h; 120 mph)—at a maximum 10,000 foot (3,000 m) altitude. He further specified that the landing gear remain deployed in the takeoff/landing position, the wing flaps be lowered 15 degrees, and the cabin remain unpressurized. Copilot William Rataczak informed Cooper that the aircraft's range was limited to approximately 1,000 miles (1,600 km) under the specified flight configuration, which meant that a second refueling would be necessary before entering Mexico. Cooper and the crew discussed options and agreed on Reno, Nevada, as the refueling stop. Finally, Cooper directed that the plane take off with the rear exit door open and its staircase extended. Northwest's home office objected, on grounds that it was unsafe to take off with the aft staircase deployed. Cooper countered that it was indeed safe, but he would not argue the point; he would lower it himself once they were airborne.

An FAA official requested a face-to-face meeting with Cooper aboard the aircraft, which was denied. The refueling process was delayed because of a vapor lock in the fuel tanker truck's pumping mechanism, and Cooper became suspicious; but he allowed a replacement tanker truck to continue the refueling—and a third after the second ran dry.

Back in the air

Boeing 727 with the aft airstair open

At approximately 7:40 pm the 727 took off with only Cooper, pilot Scott, flight attendant Mucklow, copilot Rataczak, and flight engineer H. E. Anderson aboard. Two F-106 fighter aircraft scrambled from nearby McChord Air Force Base followed behind the airliner, one above it and one below, out of Cooper's view. A Lockheed T-33 trainer, diverted from an unrelated Air National Guard mission, also shadowed the 727 until it ran low on fuel and turned back near the Oregon–California border.

After takeoff Cooper told Mucklow to join the rest of the crew in the cockpit and remain there with the door closed. As she complied, Mucklow observed Cooper tying something around his waist. At approximately 8:00 pm a warning light flashed in the cockpit, indicating that the aft airstair apparatus had been activated. The crew's offer of assistance via the aircraft's intercom system was curtly refused. The crew soon noticed a subjective change of air pressure, indicating that the aft door was open.

At approximately 8:13 pm the aircraft's tail section sustained a sudden upward movement, significant enough to require trimming to bring the plane back to level flight. At approximately 10:15 pm Scott and Rataczak landed the 727, with the aft airstair still deployed, at Reno Airport. FBI agents, state troopers, sheriff's deputies, and Reno police surrounded the jet, as it had not yet been determined with certainty that Cooper was no longer aboard; but an armed search quickly confirmed that he was gone.

Investigation

Aboard the airliner FBI agents recovered 66 unidentified latent fingerprints, Cooper's black clip-on tie and mother of pearl tie clip, and two of the four parachutes, one of which had been opened and two shroud lines cut from its canopy. Eyewitnesses in Portland, Seattle, and Reno, and all individuals who personally interacted with Cooper were interviewed. A series of composite sketches was developed.

Local police and FBI agents immediately began questioning possible suspects. One of the first was an Oregon man with a minor police record named D. B. Cooper, contacted by Portland police on the off-chance that the hijacker had used his real name, or the same alias in a previous crime. His involvement was quickly ruled out; but an inexperienced wire service reporter (Clyde Jabin of UPI by most accounts, Joe Frazier of AP by others), rushing to meet an imminent deadline, confused the eliminated suspect's name with the pseudonym used by the hijacker. The mistake was picked up and repeated by numerous other media sources, and the moniker "D. B. Cooper" became lodged in the public's collective memory.

An animation of the 727's rear airstair, deploying in flight. The gravity-operated apparatus remained open until the aircraft landed. (Click to view animation)

A precise search area was difficult to define, as even small differences in estimates of the aircraft's speed, or the environmental conditions along the flight path (which varied significantly by location and altitude), changed Cooper's projected landing point considerably. An important variable was the length of time he remained in free fall before pulling his rip cord—if indeed he succeeded in opening a parachute at all. Neither of the Air Force fighter pilots saw anything exit the airliner, either visually or on radar, nor did they see a parachute open; but at night, with extremely limited visibility and cloud cover obscuring any ground lighting below, an airborne human figure clad entirely in black clothing could easily have gone undetected. The T-33 pilots never made visual contact with the 727 at all.

An experimental re-creation was conducted using the same aircraft hijacked by Cooper in the same flight configuration, piloted by Scott. FBI agents, pushing a 200-pound (91 kg) sled out of the open airstair, were able to reproduce the upward motion of the tail section described by the flight crew at 8:13 pm. Based on this experiment, it was concluded that 8:13 pm was the most likely jump time. At that moment the aircraft was flying through a heavy rainstorm over the Lewis River in southwestern Washington.

Initial extrapolations placed Cooper's landing area on the southernmost outreach of Mount St. Helens, a few miles southeast of Ariel, Washington, near Lake Merwin, an artificial lake formed by a dam on the Lewis River. Search efforts focused on Clark and Cowlitz Counties, encompassing the terrain immediately south and north, respectively, of the Lewis River in southwest Washington. FBI agents and Sheriff's deputies from those counties searched large areas of the mountainous wilderness on foot and by helicopter. Door-to-door questioning and searches of local farmhouses were also carried out. Other search parties ran patrol boats along Lake Merwin and Yale Lake, the reservoir immediately to its east. No trace of Cooper, nor any of the equipment presumed to have left the aircraft with him, was found.

The FBI also coordinated an aerial search, using fixed-wing aircraft and helicopters from the Oregon Army National Guard, along the entire flight path (known as Victor 23 in standard aviation terminology but "Vector 23" in most Cooper literature) from Seattle to Reno. While numerous broken treetops and several pieces of plastic and other objects that, from the air, resembled parachute canopies were sighted and investigated, nothing relevant to the hijacking was found.

In early 1972, shortly after the spring thaw, teams of FBI agents aided by some 200 Army soldiers from Fort Lewis, along with Air Force personnel, National Guard troops, and civilian volunteers, conducted another thorough ground search of Clark and Cowlitz Counties for eighteen days in March, and then an additional eighteen days in April. Electronic Explorations Company, a marine salvage firm, used a submarine to search the 200-foot (61 m) depths of Lake Merwin. Two local women stumbled upon a skeleton in an abandoned structure in Clark County; it was later identified as the remains of a female teenager who had been abducted and murdered several weeks before. Ultimately, the search operation—arguably the most extensive, and intensive, in U.S. history—uncovered no significant material evidence related to the hijacking.

Later developments

Subsequent analyses called the original landing zone estimate into question: Scott, who was flying the aircraft manually because of Cooper's speed and altitude demands, later determined that his flight path was significantly farther east than initially assumed. Additional data from a variety of sources—in particular Continental Airlines pilot Tom Bohan, who was flying four minutes behind Flight 305—indicated that the wind direction factored into drop zone calculations had been wrong, possibly by as much as 80 degrees. This and other supplemental data suggested that the actual drop zone was probably south-southeast of the original estimate, in the drainage area of the Washougal River.

"I have to confess," wrote retired FBI chief investigator Ralph Himmelsbach in his 1986 book, "if I [were] going to look for Cooper, I would head for the Washougal." The Washougal Valley and its surroundings have been searched by multiple private individuals and groups in subsequent years; to date, nothing directly traceable to the hijacking has been found.

Search for ransom money

In late 1971 the FBI distributed lists of the ransom serial numbers to financial institutions, casinos, race tracks, and other businesses routinely conducting significant cash transactions, and to law enforcement agencies around the world. Northwest Orient offered a reward of 15 percent of the recovered money, to a maximum of $25,000. In early 1972 U.S. Attorney General John Mitchell released the serial numbers to the general public. In 1972 two men used counterfeit 20-dollar bills printed with Cooper serial numbers to swindle $30,000 from a Newsweek reporter named Karl Fleming in exchange for an interview with a man they falsely claimed was the hijacker.

In early 1973, with the ransom money still missing, The (Portland) Oregon Journal republished the serial numbers and offered $1,000 to the first person to turn in a ransom bill to the newspaper or any FBI field office. In Seattle, the Post-Intelligencer made a similar offer with a $5,000 reward. The offers remained in effect until Thanksgiving 1974, and while there were several near-matches, no genuine bills were found. In 1975 Northwest Orient's insurer, Global Indemnity Co., complied with an order from the Minnesota Supreme Court and paid the airline's $180,000 claim on the ransom money.

Statute of limitations

In 1976 discussion arose over impending expiration of the statute of limitations on the hijacking. Most published legal analysis agreed that it would make little difference, as interpretation of the statute varies considerably from case to case and court to court, and a prosecutor could argue that Cooper had forfeited immunity on any of several valid technical grounds. The question was rendered moot in November when a Portland grand jury returned an indictment in absentia against "John Doe, aka Dan Cooper" for air piracy and violation of the Hobbs Act. The indictment formally initiated prosecution that can be continued, should the hijacker be apprehended, at any time in the future.

Physical evidence

In 1978 a placard containing instructions for lowering the aft stairs of a 727 was found by a deer hunter near a logging road about 13 miles (21 km) east of Castle Rock, Washington, well north of Lake Merwin, but within the basic path of Flight 305.

Portion of Brian Ingram's 1980 discovery

In February 1980 an eight-year-old boy named Brian Ingram, vacationing with his family on the Columbia River about 9 miles (14 km) downstream from Vancouver, Washington, and 20 miles (32 km) southwest of Ariel, uncovered three packets of the ransom cash, significantly disintegrated but still bundled in rubber bands, as he raked the sandy riverbank to build a campfire. FBI technicians confirmed that the money was indeed a portion of the ransom—two packets of 100 twenty-dollar bills each, and a third packet of 90, all arranged in the same order as when given to Cooper.

The discovery launched several new rounds of conjecture, and ultimately raised many more questions than it answered. Initial statements by investigators and scientific consultants were founded on the assumption that the bundled bills washed freely into the Columbia River from one of its many connecting tributaries. An Army Corps of Engineers hydrologist noted that the bills had disintegrated in a "rounded" fashion, and were matted together, indicating that they had been deposited by river action, as opposed to having been deliberately buried. If so, it confirmed that Cooper had not landed near Lake Merwin, nor in any other part of the Lewis River, which feeds into the Columbia well downstream from the discovery site; and it lent credence to supplemental speculation (see Later developments above) placing the drop zone near the Washougal River, which merges with the Columbia upstream from the discovery site.

But the "free floating" hypothesis presented its own difficulties; it did not explain the ten bills missing from one packet, nor was there a logical reason that the three packets would have remained together after separating from the rest of the money. Physical evidence was incompatible with geologic evidence: Himmelsbach observed that free-floating bundles would have had to wash up on the bank "within a couple of years" of the hijacking; otherwise the rubber bands would have long since deteriorated, an observation confirmed experimentally by the Cooper Research Team (see Ongoing investigation below). Geologic evidence suggested, however, that the bills arrived at the area of their discovery—a beach front known as Tina (or Tena) Bar—well after 1974, the year of a Corps of Engineers dredging operation on that stretch of the river. Geologist Leonard Palmer of Portland State University found two distinct layers of sand and sediment between the clay deposited on the river bank by the dredge and the sand layer in which the bills were buried, indicating that the bills arrived long after dredging had been completed. The Cooper Research Team later challenged Palmer's conclusion, citing evidence that the clay layers were natural deposits. That finding, if true, favors an arrival time of less than one year after the event (based on the rubber band experiment), but does not help to explain how the bundles got to Tina Bar, or from where they came.

Multiple alternative theories were advanced. Some surmised that the money had been found at a distant location by someone (or possibly even a wild animal), carried to the river bank, and reburied there. There was also the possibility that the money had been found on the riverbank earlier, perhaps before the dredging, and buried in a superficial sand layer at a later time. The sheriff of Cowlitz County proposed that Cooper accidentally dropped a few of the bundles on the airstair, which then blew off the aircraft after he jumped and fell into the Columbia River. One local newspaper editor theorized that Cooper, knowing he could never spend the money, dumped it in the river or buried it there (and possibly elsewhere) himself. No hypothesis offered to date satisfactorily explains all of the existing evidence: "The money continues to resist all natural explanations for how it arrived on Tena Bar."

In 1981 a human skull was unearthed along the same riverbank during excavations in search of additional evidence. Forensic pathologists eventually determined that it belonged to a woman, possibly of Native American ancestry.

In 1986, after protracted negotiations, the recovered bills were divided equally between Ingram and Northwest Orient's insurer; the FBI retained 14 examples as evidence. Ingram sold fifteen of his bills at auction in 2008 for about $37,000. To date, none of the 9,710 remaining bills has turned up anywhere in the world. Their serial numbers remain available online for public search.

In 1988 a portion of a parachute was raised from the bottom of the same stretch of the Columbia River, but FBI experts determined that it could not have been Cooper's. In 2008 children unearthed another parachute near Amboy, Washington, about 6 miles (9.7 km) due south of Lake Merwin, which proved to be of World War II-era military origin. The Columbia River ransom money and the airstair instruction placard remain the only bona fide physical evidence from the hijacking ever found outside the aircraft.

Subsequent FBI disclosures

In late 2007 the FBI announced that a partial DNA profile had been obtained from three organic samples found on the hijacker's clip-on tie in 2001, though they later acknowledged that there is no evidence that the hijacker was the source of the sample material. "The tie had two small DNA samples, and one large sample," said Special Agent Fred Gutt. "It's difficult to draw firm conclusions from these samples." The Bureau also made public a file of previously unreleased evidence, including Cooper's 1971 plane ticket from Portland to Seattle (price: $18.52 plus tax, total $20.00, paid in cash).

They also disclosed that Cooper chose the older of the two primary parachutes supplied to him, rather than the technically superior professional sport parachute; and that from the two reserve parachutes, he selected a "dummy"—an unusable unit with an inoperative ripcord intended for classroom demonstrations, although it had clear markings identifying it to any experienced skydiver as non-functional. (He cannibalized the other, functional reserve parachute, possibly using its shrouds to tie the money bag shut, and to secure the bag to his body as witnessed by Mucklow.) The FBI stressed that inclusion of the dummy reserve parachute, one of four obtained in haste from a Seattle skydiving school, was accidental. In addition the agency posted previously unreleased composite sketches and fact sheets, along with a request to the general public for information which might lead to Cooper's positive identification.

Ongoing investigation

In March 2009 the FBI disclosed that Tom Kaye, a paleontologist from the Burke Museum of Natural History and Culture in Seattle, had assembled a team of "citizen sleuths" including scientific illustrator Carol Abraczinskas and metallurgist Alan Stone. The group, now known as the Cooper Research Team, is using technology unavailable in 1971 to reinvestigate important components of the case. Using GPS and satellite imagery, they are attempting to determine if the money found by Ingram floated freely to its discovery location over time, or was found elsewhere and reburied. They have reexamined the 727's flight path from Seattle to Reno to more precisely estimate Cooper's landing zone. Using electron microscopy they examined hundreds of particles on Cooper's tie, identifying Lycopodium spores (likely from a pharmaceutical product), and fragments of bismuth and aluminum.

In November 2011 Kaye announced that particles of pure (unalloyed) titanium had also been found on the tie. He explained that titanium, which was much rarer in the 1970s than it is today, was found at that time only in metal fabrication or production facilities, or at chemical companies using it (combined with aluminum) to store extremely corrosive substances. The findings suggested, he said, that Cooper may have been a chemist or a metallurgist, or possibly an engineer or manager (the only employees who wore ties in such facilities at that time) in a metal or chemical manufacturing plant, or at a company that recovered scrap metal from those types of factories.

Theories and conjectures

FBI sketch of Cooper, with age progression

In the years since the hijacking the FBI has periodically made public some of its working hypotheses and tentative conclusions about the case, drawn from witness testimony and the scarce physical evidence.

The official physical description remains unchanged and is considered reliable. Flight attendants Schaffner and Mucklow, who spent the most time with Cooper, were interviewed on the same night in separate cities, and gave nearly identical descriptions: 5 feet 10 inches (1.78 m) to 6 feet 0 inches (1.83 m) tall, 170 to 180 pounds (77 to 82 kg), mid-40s, with close-set piercing brown eyes. Passengers and other eyewitnesses gave very similar descriptions.

Agents believe that Cooper was familiar with the Seattle area and may have been an Air Force veteran, based on testimony that he recognized the city of Tacoma from the air as the jet circled Puget Sound, and his accurate comment to Mucklow that McChord Air Force Base was approximately 20 minutes' driving time from the Seattle-Tacoma Airport—a detail most civilians would not know, or comment upon. His financial situation was very likely desperate, as extortionists and other criminals who steal large amounts of money nearly always do so, according to experts, because they need it urgently; otherwise, the crime is not worth the considerable risk. (A minority opinion is that Cooper was "a thrill seeker" who made the jump "just to prove it could be done.")

Agents theorize that he took his alias from a popular Belgian comic book series of the 1970s featuring the fictional hero Dan Cooper, a Royal Canadian Air Force test pilot who took part in numerous heroic adventures, including parachuting. (One cover from the series, reproduced on the FBI web site, depicts test pilot Cooper skydiving in full paratrooper regalia.) Because the Dan Cooper comics were never translated into English nor imported to the US, they speculate that he may have encountered them during a tour of duty in Europe. Tom Kaye's Cooper Research Team (see Ongoing investigation) has suggested the alternative possibility that Cooper was Canadian, and found the comics in Canada, where they were also sold. They note his specific demand for "negotiable American currency", a phrase seldom if ever used by American citizens; since witnesses stated that Cooper had no distinguishable accent, Canada would be his most likely country of origin if he were not a United States citizen.

The FBI task force believes that Cooper was a careful and shrewd planner. He demanded four parachutes to force the assumption that he might compel one or more hostages to jump with him, thus ensuring he would not be deliberately supplied with sabotaged equipment. He chose a 727-100 aircraft because it was ideal for a bail-out escape, due not only to its aft airstair, but also the high, aftward placement of all three engines, which allowed a reasonably safe jump without risk of immediate incineration by jet exhaust. It had "single-point fueling" capability, a recent innovation which allowed all tanks to be refueled rapidly through a single fuel port. It also had the ability (unusual for a commercial jet airliner) to remain in slow, low-altitude flight without stalling; and Cooper knew how to control its air speed and altitude without entering the cockpit, where he could have been overpowered by the three pilots. In addition, Cooper was familiar with important details, such as the appropriate flap setting of 15 degrees (which was unique to that aircraft), and the typical refueling time. He knew that the aft airstair could be lowered during flight—a fact never disclosed to civilian flight crews, since there was no situation on a passenger flight that would make it necessary—and that its operation, by a single switch in the rear of the cabin, could not be overridden from the cockpit. He may even have known that the Central Intelligence Agency had been using 727s to drop agents and supplies behind enemy lines during the Vietnam War.

Cooper's meticulous planning may also have extended to the timing of his operation, and even his choice of attire, according to Kaye's research team. "The FBI searched but couldn't find anyone who disappeared that weekend," Kaye wrote, suggesting that the perpetrator may have simply returned to his normal occupation. "If you were planning on going 'back to work on Monday', then you would need as much time as possible to get out of the woods, find transportation and get home. The very best time for this is in front of a four-day weekend, which is the timing Dan Cooper chose for his crime." Furthermore, "if he was planning ahead, he knew he had to hitchhike out of the woods, and it is much easier to get picked up in a suit and tie than in old blue jeans."

Despite his careful planning and attention to detail, the Bureau feels strongly that Cooper lacked crucial skydiving skills and experience. "We originally thought Cooper was an experienced jumper, perhaps even a paratrooper," said Special Agent Larry Carr, leader of the investigative team since 2006. "We concluded after a few years this was simply not true. No experienced parachutist would have jumped in the pitch-black night, in the rain, with a 200-mile-an-hour wind in his face, wearing loafers and a trench coat. It was simply too risky. He also missed that his reserve 'chute was only for training, and had been sewn shut—something a skilled skydiver would have checked." He also failed to bring or request a helmet, chose to jump with the older and technically inferior of the two primary parachutes supplied to him, and jumped into a −70 °F (−57 °C) wind chill.

Assuming that Cooper was not a paratrooper, but was an Air Force veteran, Carr believes that he could have been an aircraft cargo loader. Such an assignment would have given him knowledge and experience in the aviation industry; and loaders—because they throw cargo out of flying aircraft—wear emergency parachutes and receive rudimentary jump training. Such training would have given Cooper a working knowledge of parachutes—but "not necessarily sufficient knowledge to survive the jump he made."

The Bureau has argued from the beginning that Cooper did not survive his jump. "Diving into the wilderness without a plan, without the right equipment, in such terrible conditions, he probably never even got his 'chute open," said Carr. Even if he did land safely, agents contend, survival in the mountainous terrain would have been all but impossible without an accomplice at a predetermined landing point, which would have required a precisely timed jump—necessitating, in turn, cooperation from the flight crew. There is no evidence that Cooper had any such help from the crew, nor any clear idea where he was when he jumped into the stormy, overcast darkness.

Copycat hijackings

Cooper was not the first to attempt air piracy for personal gain; two weeks prior, Paul Cini did it aboard an Air Canada DC-8 over Montana, but was overpowered by the crew when he put down his gun to strap on the parachute. Cooper's apparent success inspired a flurry of imitators. Most "copycats" struck during the year that followed. Some examples:

• Garrett Brock Trapnell hijacked a TWA airliner en route from Los Angeles to New York City in January 1972. He demanded $306,800 in cash, the release of Angela Davis, and an audience with President Richard Nixon. After the aircraft landed at Kennedy Airport he was shot and wounded by FBI agents before being arrested.

• Richard Charles LaPoint, an Army veteran and "New England beach bum", boarded Hughes Airwest Flight 800 at McCarran airport in Las Vegas on January 20. Brandishing what he claimed was a bomb while the DC-9 was on the taxiway, he demanded $50,000, two parachutes, and a helmet. After releasing the passengers and two flight attendants he ordered the plane on an eastward trajectory toward Denver, then bailed out over the treeless plains of northeastern Colorado. Authorities, tracking the locator-equipped parachute and his footprints in the snow and mud, apprehended him a few hours later.
• Richard McCoy, Jr., a former Army Green Beret, hijacked a United Airlines 727-100 in April after it left Denver, Colorado, diverted it to San Francisco, then bailed out over Utah with $500,000 in ransom money. He landed safely, but was arrested two days later.
• Frederick Hahneman used a handgun to hijack an Eastern Airlines 727 in Allentown, Pennsylvania, in May, demanded $303,000, and eventually parachuted into Honduras, his country of birth. A month later, with the FBI in pursuit and a $25,000 bounty on his head, he surrendered to the American Embassy in Tegucigalpa.
• Robb Dolin Heady, a paratrooper and Vietnam veteran, stormed a United Airlines 727 in Reno in early June, extorted $200,000 and two parachutes, and jumped into darkness near Washoe Lake, about 25 miles (40 km) south of Reno. Police found Heady's car (sporting a United States Parachute Association bumper sticker) parked near the lake and arrested him as he returned to it the next morning.
• Martin McNally, an unemployed service station attendant, used a submachine gun in late June to commandeer an American Airlines 727 en route from St. Louis to Tulsa, then diverted it eastward to Indiana and bailed out with $500,000 in ransom. McNally lost the ransom money as he exited the aircraft, but landed safely near Peru, Indiana, and was apprehended a few days later in a Detroit suburb.

In all, a total of 15 hijackings similar to Cooper's—all unsuccessful—were attempted in 1972. With the advent of universal luggage searches in 1973 (see Airport security) the general incidence of hijackings dropped precipitously. There were no further notable Cooper imitators until July 11, 1980, when Glenn K. Tripp seized Northwest flight 608 at Seattle-Tacoma Airport, demanding $600,000 ($100,000 by an independent account), two parachutes, and the assassination of his boss. After a ten-hour standoff he was apprehended, but on January 21, 1983—while still on probation—he hijacked the same Northwest flight, this time en route, and demanded to be flown to Afghanistan. When the plane landed in Portland he was shot and killed by FBI agents.

Suspects

Since 1971 the FBI has processed over a thousand "serious suspects" along with assorted publicity seekers and deathbed confessors, most of whom have been definitively ruled out. Some notable examples:

Kenneth Christiansen

In 2003 a Minnesota resident named Lyle Christiansen, after watching a television documentary about the Cooper hijacking, became convinced that his late brother Kenneth was D. B. Cooper. After repeated futile attempts to convince first the FBI, and then the author and film director Nora Ephron (whom he hoped would make a movie about the case), he contacted a private investigator in New York. In 2010 the detective, Skipp Porteous, published a book postulating that Christiansen was indeed the hijacker. In early 2011 an episode of the History series Brad Meltzer's Decoded also summarized the circumstantial evidence linking Christiansen to the Cooper case.

Christiansen enlisted in the Army in 1944 and was trained as a paratrooper. The war had ended by the time he was deployed in 1945, but he made occasional training jumps while stationed in Japan with occupation forces in the late 1940s. After leaving the Army he joined Northwest Orient in 1954 as a mechanic in the South Pacific, and subsequently became a flight attendant, and then a purser, based in Seattle. Christiansen was 45 years old at the time of the hijacking, but he was shorter (5 ft. 8 in.), thinner (150 pounds), and lighter complected than eyewitness descriptions. Christiansen smoked (as did the hijacker), and displayed a particular fondness for bourbon (Cooper's preferred beverage). He was also left-handed. (Evidence photos of Cooper's black tie show the tie clip applied from the left side, suggesting a left-handed wearer.) Flight attendant Florence Schaffner told a reporter that photos of Christiansen fit her memory of the hijacker's appearance more closely than those of other suspects she had been shown. (Tina Mucklow, who had the most contact with Cooper, has never granted a press interview).

Christiansen reportedly purchased a house with cash a few months after the hijacking. While dying of cancer in 1994 he told Lyle, "There is something you should know, but I cannot tell you." Lyle said he never pressed his brother to explain. After Christiansen's death family members discovered gold coins and a valuable stamp collection, along with over $200,000 in bank accounts. They also found a folder of Northwest Orient news clippings which began about the time he was hired in the 1950s, and stopped just prior to the date of the hijacking, despite the fact that the hijacking was by far the most momentous news event in the airline's history. Christiansen continued to work part-time for the airline for many years after 1971, but apparently never clipped another Northwest news story.

Despite the publicity generated by Porteous's book and the 2011 television documentary, the FBI is standing by its position that Christiansen cannot be considered a prime suspect. They cite a poor match to eyewitness physical descriptions, a level of skydiving expertise above that predicted by their suspect profile, and an absence of direct incriminating evidence.

William Gossett

William Pratt Gossett was a Marine Corps, Army, and Army Air Force veteran who saw action in Korea and Vietnam. His military experience included advanced jump training and wilderness survival. After retiring from military service in 1973 he worked as an ROTC instructor, taught military law at Weber State University in Ogden, Utah, and hosted a radio talk show in Salt Lake City which featured discussions about the paranormal. He died in 2003.

Gossett was widely known to be obsessed with the Cooper hijacking. He amassed a voluminous collection of Cooper-related news articles, and told one of his wives that he knew enough about the case to "write the epitaph for D.B. Cooper". Late in his life he reportedly told three of his sons, a retired Utah judge, and a friend in the Salt Lake City public defender's office that he had committed the hijacking. Photos of Gossett taken circa 1971 bear a close resemblance to the most widely circulated Cooper composite drawing.

According to Galen Cook, a lawyer who has collected information related to Gossett for years, Gossett once showed his sons a key to a Vancouver, British Columbia safe deposit box which, he claimed, contained the long-missing ransom money. Gossett's eldest son, Greg, said that his father, a compulsive gambler who was always "strapped for cash", showed him "wads of cash" just before Christmas 1971, weeks after the Cooper hijacking. He speculated that Gossett gambled the money away in Las Vegas.

In 1988 Gossett changed his name to "Wolfgang" and became a Catholic priest, which Cook and others interpreted as an effort to disguise his identity. Other circumstantial evidence includes testimony that Cook claims to have obtained from William Mitchell, a passenger on the hijacked aircraft, regarding a mysterious "physical detail" (which he will not divulge) common to the hijacker and Gossett. Cook also claims to have found "possible links" to Gossett in each of four letters signed by "D.B. Cooper" and mailed to three newspapers within days after the hijacking, although there is no evidence that the actual hijacker created or mailed any of the letters.

The FBI has no direct evidence implicating Gossett, and cannot even reliably place him in the Pacific Northwest at the time of the hijacking. "There is not one link to the D.B. Cooper case," said Special Agent Carr, "other than the statements [Gossett] made to someone."

Richard Floyd McCoy, Jr.

Main article: Richard McCoy, Jr.

McCoy was an Army veteran who served two tours of duty in Vietnam, first as a demolition expert, and later, with the Green Berets, as a helicopter pilot. After his military service he became a warrant officer in the Utah National Guard and an avid recreational skydiver, with aspirations, he said, of becoming a Utah State Trooper.

On April 7, 1972 McCoy staged the best-known of the so-called "copycat" hijackings (see above). He boarded United Airlines' Flight 855 (a Boeing 727 with aft stairs) in Denver, and brandishing what later proved to be a paperweight resembling a hand grenade and an unloaded handgun, he demanded four parachutes and $500,000. After delivery of the money and parachutes at San Francisco International Airport, McCoy ordered the aircraft back into the sky and bailed out over Provo, Utah, leaving behind his handwritten hijacking instructions and his fingerprints on a magazine he had been reading. He was arrested on April 9 with the ransom cash in his possession, and after trial and conviction, received a 45-year sentence. Two years later he escaped from Lewisburg Federal Penitentiary with several accomplices by crashing a garbage truck through the main gate. Tracked down three months later in Virginia Beach, McCoy was killed in a shootout with FBI agents.

In their 1991 book, D.B. Cooper: The Real McCoy, parole officer Bernie Rhodes and former FBI agent Russell Calame asserted that they had identified McCoy as D.B. Cooper. They cited obvious similarities in the two hijackings, claims by McCoy's family that the tie and mother-of-pearl tie clip left on the plane belonged to McCoy, and McCoy's own refusal to admit or deny that he was Cooper. A principal proponent of their theory was the FBI agent who killed McCoy. "When I shot Richard McCoy," he said, "I shot D. B. Cooper at the same time."

While there is no reasonable doubt that McCoy committed the Denver hijacking, the FBI does not consider him a suspect in the Cooper case because of significant mismatches in his age (29) and description; a level of skydiving skill well above that thought to be possessed by the hijacker; and credible evidence that McCoy was in Las Vegas on the day of the Seattle hijacking, and at home in Utah the day after, having Thanksgiving dinner with his family.

Duane Weber

Duane L. Weber was a World War II Army veteran who served time in at least six prisons from 1945 to 1968 for burglary and forgery. He was proposed as a suspect by his widow, based primarily on a deathbed confession: Three days before he died in 1995, Weber told his wife, "I am Dan Cooper." The name meant nothing to her, she said; but months later, a friend told her of its significance in the hijacking. She went to her local library to research D.B. Cooper, found Max Gunther's book, and discovered notations in the margins in her husband's handwriting.

She then recalled, in retrospect, that Weber once had a nightmare during which he talked in his sleep about jumping from a plane, leaving his fingerprints on the "aft stairs". He also reportedly told her that an old knee injury had been incurred by "jumping out of a plane". Like the hijacker, Weber drank bourbon and chain smoked. Other circumstantial evidence included a 1979 trip to Seattle and the Columbia River, during which Weber took a walk alone along the river bank in the Tina Bar area; four months later Brian Ingram made his ransom cash discovery in the same area.

The FBI eliminated Weber as an active suspect in July 1998 when his fingerprints did not match any of those processed in the hijacked plane, and no other direct evidence could be found to implicate him. Later, his DNA also failed to match the samples recovered from Cooper's tie, though the Bureau has since conceded that they cannot be certain that the organic material on the tie came from Cooper.

John List

Main article: John List

John Emil List was an accountant and World War II and Korea veteran who murdered his wife, three teenage children, and 85-year-old mother in Westfield, New Jersey fifteen days before the Cooper hijacking, withdrew $200,000 from his mother's bank account, and disappeared. He came to the attention of the Cooper task force due to the timing of his disappearance, multiple matches to the hijacker's description, and the reasoning that "a fugitive accused of mass murder has nothing to lose." After his capture in 1989, List admitted to murdering his family, but denied any involvement in the Cooper hijacking. While his name continues to crop up in Cooper articles and documentaries, no direct evidence implicates him, and the FBI no longer considers him a suspect. He died in prison in 2008.

Barbara Dayton

Barbara Dayton, a recreational pilot and University of Washington librarian who was born Robert Dayton, served in the Merchant Marine in 1926 and then the Army during World War II. After discharge Dayton worked with explosives in the construction industry and aspired to a professional airline career, but could not obtain a commercial pilot's license.

Dayton underwent gender reassignment surgery in 1969 and changed her name to Barbara. She claimed to have staged the Cooper hijacking two years later, disguised as a man, in order to "get back" at the airline industry and the FAA, whose insurmountable rules and conditions had prevented her from becoming an airline pilot. She said she hid the ransom money in a cistern near her landing point in Woodburn, a suburban area south of Portland, Oregon. Eventually she recanted her entire story, ostensibly after learning that she could still be charged with the hijacking. The FBI has never commented publicly on Dayton, who died in 2002.

Ted Mayfield

Mayfield is an Army Special Forces veteran, former pilot, competitive skydiver, skydiving instructor, and ex-convict who served time for negligent homicide after two of his students died when their parachutes failed to open. His criminal record also includes armed robbery and transportation of stolen aircraft, and in 2010 he was sentenced to three years' probation for flying a single-engine plane, 26 years after permanent revocation of his pilot's license. He was suggested repeatedly as a suspect early in the investigation, according to FBI Agent Ralph Himmelsbach, who knew Mayfield from a prior dispute at a local airport. He was ruled out, based partly on the fact that he called Himmelsbach less than two hours after Flight 305 landed in Reno to volunteer advice on standard skydiving practices and possible landing zones.

In 2006 two amateur researchers named Daniel Dvorak and Matthew Myers proposed him as a suspect once again, attracting coverage from a Portland television station and the syndicated program Inside Edition. They asserted that they had assembled a convincing circumstantial case that would be presented in detail in a forthcoming book. Among other things, they theorized that Mayfield called Himmelsbach not to offer advice, but to establish an alibi; and they challenged Himmelsbach's conclusion that Mayfield could not possibly have found a phone in time to call the FBI less than four hours after jumping into the wilderness at night. Mayfield denied any involvement, and repeated a previous assertion that the FBI called him five times while the hijacking was still in progress to ask about skydiving techniques. (Himmelsbach said the FBI never called Mayfield.) Mayfield further charged that Dvorak and Myers asked him to play along with their theory, and "we'll all make a lot of money." (Dvorak and Myers called any inference of collusion a "blatant lie.")

Dvorak died in 2007, and to date, the promised book has not been published. The FBI has offered no comment beyond Himmelsbach's original statement that Mayfield, who still resides in Sheridan, Oregon, was ruled out as a suspect early on.

Jack Coffelt

Coffelt was a conman, ex-convict, and purported government informant who claimed to have been the chauffeur and confidante of Abraham Lincoln's last undisputed descendant, great-grandson Robert Todd Lincoln Beckwith. In 1972 he began claiming he was D.B. Cooper, and attempted through an intermediary, a former cellmate named James Brown, to sell his story to a Hollywood production company. He said he landed near Mount Hood, about 50 miles (80 km) southeast of Ariel, injuring himself and losing the ransom money in the process. Photos of Coffelt bear a resemblance to the composite drawings, although he was in his mid-fifties in 1971. He was reportedly in Portland on the day of the hijacking, and sustained leg injuries around that time which were consistent with a skydiving mishap.

Coffelt's account was reviewed by the FBI, which concluded that it differed in significant details from information that had not been made public, and was therefore a fabrication. Brown, undeterred, continued peddling the story long after Coffelt died in 1975. Multiple media venues, including the television news program 60 Minutes, considered and rejected it. In a 2008 book about Lincoln's descendants, author Charles Lachman revisited Coffelt's tale although it had been discredited 36 years before.

Lynn Doyle Cooper

L.D. Cooper, a leather worker and Korean War veteran, was proposed as a suspect in July 2011 by his niece, Marla Cooper. As an 8-year-old, she recalled Cooper and another uncle planning something "very mischievous", involving the use of "expensive walkie-talkies", at her grandmother's house in Sisters, Oregon, 150 miles (240 km) south of Portland. The next day flight 305 was hijacked; and though the uncles ostensibly were turkey hunting, L.D. Cooper came home wearing a bloody shirt—the result, he said, of an auto accident. Later, she said, her parents came to believe that L.D. Cooper was the hijacker. She also recalled that her uncle, who died in 1999, was obsessed with the Canadian comic book hero Dan Cooper (see Theories and conjectures), and "had one of his comic books thumbtacked to his wall"—although he was not a skydiver or paratrooper.

In August New York magazine published an alternative witness sketch, reportedly based on a description by Flight 305 eyewitness Robert Gregory, depicting horn-rimmed sunglasses, a "russet"-colored suit jacket with wide lapels, and marcelled hair. The article notes that L.D. Cooper had wavy hair that looked marcelled (as did Duane Weber).

On August 3 the FBI announced that no fingerprints had been found on a guitar strap made by L.D. Cooper. One week later they added that his DNA did not match the partial DNA profile obtained from the hijacker's tie, but acknowledged, once again, that there is no certainty that the hijacker was the source of the organic material obtained from the tie. The Bureau has made no further public comment.

Aftermath

Airport security

The Cooper hijacking marked the beginning of the end for unfettered and unscrutinized airline travel. Despite initiation of the federal Sky Marshal program the previous year, 31 hijackings were committed in U.S. airspace in 1972, 19 of them for the specific purpose of extorting money. (Most of the rest were attempts to reach Cuba.) In 15 of the extortion cases the hijackers also demanded parachutes. In early 1973 the FAA began requiring airlines to search all passengers and their bags. Amid multiple lawsuits charging that such searches violated Fourth Amendment protections against search and seizure, federal courts ruled that they were acceptable when applied universally, and when limited to searches for weapons and explosives. In contrast to the 31 hijackings in 1972, only two were attempted in 1973, both by psychiatric patients, one of whom intended to crash the airliner into the White House to kill President Nixon.

Aircraft modifications

In the wake of multiple "copycat" hijackings in 1972 the FAA required that all Boeing 727 aircraft be fitted with a device, later dubbed the "Cooper vane", which prevented lowering of the aft airstair during flight. Several airlines elected to abandon use of the airstair entirely, and simply welded the aft doors of their 727s shut.

A less-well-known modification mandated as a direct result of the hijacking was the installation of peepholes in all cockpit doors, making it possible for the cockpit crew to observe events in the passenger cabin with the cockpit door closed.

Subsequent history of N467US

In 1978 the hijacked 727-100 aircraft was sold by Northwest to Piedmont Airlines where it was reregistered N838N and continued in domestic carrier service. In 1984 it was purchased by the now-defunct charter company Key Airlines, reregistered N29KA, and incorporated into the Air Force's civilian charter fleet that shuttled workers between Nellis Air Force Base and the Tonopah Test Range during the top-secret F-117 Nighthawk development program. In 1996 the aircraft was scrapped for parts in a Memphis boneyard.

Earl Cossey

In late April 2013 Earl Cossey, the owner of the skydiving school that furnished the four parachutes given to Cooper, was found dead in his home in Woodinville, a suburb of Seattle. His death was ruled a homicide due to blunt-force trauma to the head. The perpetrator remains unknown. Conspiracy theorists immediately began pointing out possible links to the Cooper case, but authorities responded that they have no reason to believe that any such link exists. Woodinville officials later announced that the most likely motive for the crime was burglary.

Cultural phenomena

Main article: D. B. Cooper in popular culture

While D.B. Cooper was an air pirate and extortionist (Himmelsbach famously called him a "rotten sleazy crook") who endangered the lives of 42 people and caused immeasurable inconvenience for many others, his bold, adventurous, unprecedented crime inspired a cult following, expressed through song, film and literature. Cities in the Pacific Northwest sold tourist souvenirs and held celebrations in his memory. He is remembered in Ariel, Washington, with a "Cooper Day" event held annually on the weekend after Thanksgiving weekend, and elsewhere with Cooper-themed promotions held by restaurants and bowling alleys. Cooper has also been used in the storylines of such popular TV series as Prison Break, White Collar, NewsRadio, and Numb3rs, as well as a book titled The Vesuvius Prophecy, based on The 4400 TV series.

In 2013, NewTV's Original Program The Folklorist produced a segment titled The Legend of DB Cooper.

See also

• Cold case (criminology)
• List of people who disappeared mysteriously

Further reading

• Tosaw, Richard T. (1984) D.B. Cooper: Dead or Alive?. Tosaw Publishing. ISBN 0-9609016-1-2. (Early compendium of information, some at variance with later, more authoritative accounts; self-published; includes a complete listing of ransom serial numbers.)
• Gunther, Max (1985). D. B. Cooper: What Really Happened. Chicago: Contemporary Books. ISBN 0-8092-5180-9. {{cite book}}: Invalid |ref=harv (help) (Based on interviews with a woman known as "Clara", who claimed to have discovered an injured Cooper two days after the hijacking and lived with him until he died a decade later; considered a hoax by the FBI.)
• Himmelsbach, Ralph P.; Worcester, Thomas K. (1986). Norjak: The Investigation of D. B. Cooper. West Linn, Oregon: Norjak Project. ISBN 978-0-9617415-0-1. {{cite book}}: Invalid |ref=harv (help) (Himmelsbach was the FBI's chief investigator on the case until his retirement in 1980; "Norjak" is FBI shorthand for the Cooper hijacking.)
• Rhodes, B and Calame, R. (1991) D.B. Cooper: The Real McCoy. Univ. of Utah Press ISBN 0-87480-377-2. (Summary of the circumstantial case that "copycat" Richard McCoy was D.B. Cooper.)
• Reid, Elwood (2005). D.B.: A Novel. Anchor Books. ISBN 0-385-49739-3 (A work of fiction which proposes a factually unsupported solution to the hijacking.)
• Forman, P and Forman, R. (2008) The Legend of D.B. Cooper – Death by Natural Causes. Borders Personal Publishing. ISBN 1-60552-014-4 (The self-published story of Barbara Dayton, who claimed to have staged the hijacking disguised as a man, then recanted her story.)
• Grant, Walter. (2008) D.B. Cooper, Where Are You? Publication Consultants. ISBN 1-59433-076-X (A writer's fanciful account of what may have happened.)
• Nuttall, George C. (2010) D.B. Cooper Case Exposed: J. Edgar Hoover Cover Up? Vantage Press. ISBN 0-533-16390-0 (Factually unsupported theory of conspiracy and cover-up.)
• Olson, Kay Melchisedech (2010). D.B. Cooper Hijacking: Vanishing Act. Compass Point Books. ISBN 0-7565-4359-2. {{cite book}}: Invalid |ref=harv (help) (Straightforward accounting of official information and evidence.)
• Elmore, Gene. (2010) D.B. Cooper: Aftermath. iUniverse. ISBN 1-4502-1545-9 (Self-published work of fiction, interwoven with some of the commonly known facts.)
• Porteous, Skipp; Blevins, Robert M. (2010). Into the Blast – The True Story of D.B. Cooper. Seattle, Washington: Adventure Books of Seattle. ISBN 978-0-9823271-8-0. {{cite book}}: Invalid |ref=harv (help) (A compilation of the circumstantial evidence implicating Kenneth Christiansen.)
• Gray, Geoffrey. (2011) Skyjack: The Hunt for D.B. Cooper. Crown. ISBN 0-307-45129-1 (A newly published book by the author of the 2007 New York Magazine article that proposed Kenneth Christiansen as a suspect.)

External links

• FBI Reading Room Files of the D.B. Cooper Case
• Radio interviews about D. B. Cooper's identity with major authors
• November 27, 1971, account of the hijacking in the Minneapolis Tribune
• Radio interview with F.B.I. lead investigator Larry Carr
• PCGS Currency Notifies F.B.I. of "D. B. Cooper" Serial Numbers
• Fifteen D.B. Cooper $20 Notes make $37K at Auction
• Northwest 305 Hijacking Research Site
• "Hijacking Myth #3" in Fortnight Journal