AV Technician Dave Benton (Wes Ramsey, seasons 7–10): The current audio/visual tech for the Miami Dade Crime Lab, who is a rock-star type of guy. (Ramsey had previously appeared as Kip Martin in the season 1 episode, "Spring Break".)
Laboratory Technician Michael Travers (Christopher Redman, seasons 7–10): British trace analyst. He has a background knowledge about horse racing which was helpful for a case (713, And They're Offed). He always seemed to be nosy about what was going on about a case, but showed he cares about the team.
Laboratory Technician Sam Belmontes (Cristian de la Fuente, seasons 1–2, 10): Chemical Analysis lab tech.
Laboratory Technician Carrie Delgado (Nicole DeHuff, season 2): Blood evidence technician. She was a fan of Quincy, M.E. as a child, influencing her to become a criminalist. She only appeared in season 2, as two years later, DeHuff died from pneumonia.
Laboratory Technician Tyler Jenson (Brian Poth, seasons 1–3): Audio/visual and multimedia lab technician who was later replaced by Dan Cooper.
Laboratory Technician Joseph Kayle (Leslie Odom Jr., seasons 2–4): A lab tech who worked in fingerprints.
Laboratory Technician Maxine Valera (Boti Bliss, seasons 2–8): DNA analyst. She was temporarily suspended from her duties in season 3 for technical errors and was then reinstated by season 4. She has an unfortunate habit of taking shortcuts with evidence, which caused her suspension and also brought her under suspicion when the lab was investigated by the FBI (episode 425, "One of Our Own"). She goes on a date with Natalia Boa Vista's ex-husband, Nick Townsend, and thinks she is his killer after he turns up murdered, though this assumption is proved to be untrue. Jake Berkley (who investigated the case) kept insisting she and Natalia had killed him, despite the fact that Townsend was brutally beaten to death. She and Natalia were cleared, however, when it is revealed that Nick Townsend's death is related to the case of Lauren Sloan and her husband Jeff Murdock. Jeff killed Nick to get back his wife's earring (episode 512, "Internal Affairs"). Her final appearance was in "Delko for the Defense".
Laboratory Technician Jim Markham (Joshua Leonard, season 4), Ballistic lab tech. Markham became the head of the ballistics section when Calleigh left after John Hagan committed suicide there, but unfortunately, Markham made regular mistakes such as leaving skin cells unexamined on a bullet casing. Calleigh later grew tired of Markham screwing up and returned to the Ballistics lab, which also resulted in Markham being transferred elsewhere.
Laboratory Technician Aaron Peters (Armando Valdes-Kennedy, seasons 3–4): A trace evidence lab tech. He did not like Eric Delko in his lab while working his sister's case being in his lab. He filed a report, but later regretted it when the lab falls under federal investigation. Presumably, as a result of the intense pressure the FBI was giving the Crime Lab, Peters most likely quit his job or at his own request was transferred to work elsewhere.
Laboratory Technician Nicole Talcott (Kimiko Gelman, season 5): A lab tech from the night shift of the Miami Dade Crime Lab. She temporarily filled in for Valera after the latter was suspended for putting a rape victim's DNA and profile into the system.
Audio/Visual laboratory technician Daniel "Dan" Cooper (Brendan Fehr, seasons 4–6): He believes a great deal of information can be discerned by what music a person has on his or her MP3 playlist (episode 517, "A Grizzly Murder"). He had a good relationship with the Crime Lab personnel and also the CSIs until the season 6 episode "Bang, Bang, Your Debt", when he is discovered to have stolen and used a credit card that belonged to the late Tim Speedle—to the outrage of Delko and Calleigh, who told him to turn himself in or she would issue a warrant for his arrest. Presumably, this instance of identity theft was the final nail in the coffin for Cooper and ended his career at the lab, prompting him to resign from the lab for good, in disgrace. As a result, he holds a personal grudge against Calleigh for this, despite the fact that she does not press charges, and steals the flashcard out of her camera at a crime scene to put the pictures on a website he has created to "take her down a notch." He also changes her cell number and posts it on the site, and she is kidnapped from a "lead" (episode 615, "All In"). After an enraged Delko confronts him, Cooper later feels remorseful and turns in evidence that helps the team track down Calleigh, free her, and arrest her kidnappers.
Medical Examiner Tom Loman (Christian Clemenson, seasons 8–10): The current medical examiner. Despite the macabre nature of his work, he seems genuinely excited by it, even performing an autopsy on the fly for some medical students on a cadaver donated to science, which was eventually discovered to be a victim of a crime the CSIs were investigating. In contrast to his usually upbeat demeanor, he does occasionally lament at how violent people can be to each other.
MDPD Homicide/Robbery Unit: Detective Jake Berkeley (Johnny Whitworth, seasons 5–8): An undercover officer with the MDPD narcotics unit. As of episode 512 ("Internal Affairs"), he has moved to being a homicide detective. He and Calleigh dated while they were in the Academy. At the end of season 5 and in season 6, they had again begun a relationship, but new department regulations involving officer fraternization and pressure from Rick Stetler caused Berkeley to break things off. He resumed his undercover duty in episode 821 ("Meltdown"), tracking a gang of diamond thieves.
MDPD Homicide/Robbery Unit: Detective John Hagen (Holt McCallany, seasons 1–3): A homicide detective who had emotional and psychological problems. He was also Raymond Caine's partner prior to his faked death. He told Calleigh once that he could not stand being reminded of being the partner of a dirty cop. He also had a brief relationship with Calleigh in season 2. While pulling a crucial piece of evidence from a crime scene, he panicked when Calleigh came over to photograph the scene; he then crept up behind her and put his gun behind her head. Although he did not mean to hurt her, it allowed him time to escape (she did not know it was him at that time). He later shot himself in the Ballistics Lab right after Calleigh turned around to walk out of the lab during the season 3 finale.
MDPD Homicide/Robbery Unit: Detective Adelle Sevilla (Wanda de Jesus, season 1): A Latina homicide detective who occasionally accompanies the CSIs. She appeared in ten episode of season 1 and is fluent in Spanish.
MDPD Homicide/Robbery Unit: Detective Bernstein (Michael Whaley, season 1): An African-American detective who also accompanies the CSIs to various crime scenes.
MDPD Officer Aaron Jessop (Joel West, seasons 2, 4): A patrol officer, Jessop joined the force during season 2 and his first appearance was in "The Oath". While he thought like a cop, he also was able to think like a CSI. This was evident in "The Oath", where he was able to help Calleigh assess the crime scene and upped the charge and penalty. Jessop was killed when he opened a cabinet rigged with a hand grenade booby trap at the scene of a Mala Noche shootout, leaving Horatio and the other CSIs distraught at his death. (West had previously appeared as Officer Ramirez in the season 2 episode "Big Brother")
Raymond Caine, Sr. (Dean Winters) and (Chistopher Stapleton): Horatio's brother who faked his death while working undercover. He is eventually reunited with his wife, Yelina Salas, and son Ray Jr. with the three flying to Rio to start a new life for themselves. Unfortunately, Ray's attempts to get clean fail, and over time, he becomes involved with the Mala Noche and is later beaten to death by Antonio Riaz, and dies in Horatio's arms, but not before urging Horatio to save Ray Jr.
Raymond Caine, Jr. (Alex Buck, Hayden Tank, and Carter Jenkins, seasons 1–5), Horatio's nephew, son of Yelina and Raymond Caine (Horatio's brother). He is first introduced in "Grave Young Men", when Horatio finds out that he has been getting to fights at school. He tells Horatio that he has been fighting because people keep calling his dad a "dirty cop", to which Horatio replies, "You know that's not true". He appears in "Hell Night", it is discovered that a homeless man died from a heart attack after being shot with a paintball gun, and Ray Jr. becomes the primary suspect. However, he is cleared when a tape reveals that he asked the shooter to stop. He is seen at the end of "Nothing To Lose" when he donates bone marrow to save Madison Keaton, who is terminally ill. Then, Yelina finds out Madison is in fact Ray's daughter, not Horatio's. He is briefly seen in "Whacked" when Horatio goes to Yelina's house. When he arrives there, Sergeant Rick Stetler is leaving. Shortly afterward, Ray Jr. expresses resentment toward Stetler. He is seen again in "10-7", the season 3 finale, when he is kidnapped by people who are trying to flush his father out of hiding. They are later reunited and fly to Brazil. On the season 5 premiere, "Rio", Mala Noche leader Antonio Riaz is revealed to have tried to involve Ray Jr. in a drug-running scheme. Horatio kills Riaz, but not before Riaz murders Ray Sr. Ray Jr. has not been seen since season 5, but he is assumed to be back in Miami with Yelina.
Madison Keaton (Kyndell Rose Crowell) (seasons 1–3): The illegitimate daughter of Raymond Caine and Susie Barnam Keaton (episode 208, "Big Brother"). In a later episode, Madison becomes terminally ill. Neither Horatio nor Susie are matches for a bone marrow transplant. Horatio convinces Yelina Salas (who had assumed Madison was Horatio's daughter before Horatio told her the truth) to have her son tested. Presumably, Ray Jr. is tested and proves to be a match, and Madison is cured.
Susie Barnam Keaton (Azura Skye, seasons 1–3): A meth addict who became involved in Horatio's personal life after revealing she had known his late brother (Raymond). After Susie rehabs in Indiana and returns to Miami, Horatio learns that her daughter (Madison) is Raymond's child (episode 208, "Big Brother").
Marisol Delko Caine (née Delektorsky) (Alana de la Garza, season 4, 10 premiere): Eric Delko's older sister, who had cancer. Because of the painful treatments, Eric occasionally bought medical cannabis to alleviate her pain and nausea. Afterwards, Eric helped to feed her when she had no appetite. Eric's friends and colleagues found out when the drug dealer ruined a crime scene by dropping though a skylight and then trying to save himself by mentioning that Eric brought drugs from him, although Frank Tripp at first insisted the information was "a load of crap". Unfortunately, it was the truth, and shortly thereafter Rick Steler began investigating. Over time, Marisol and Horatio developed a romantic relationship and later got married between the episodes "Shock" and "Rampage". She was shot by a Mala Noche sniper during the "Rampage" episode, and later died from her injury, leaving Horatio and Delko both grief-stricken, devastated, and hellbent on seeking revenge for Marisol's death. Later, the hit was discovered to have been ordered by a Mala Noche boss named Antonio Riaz, who found out about Marisol's family connections through his relationship as her marijuana dealer. Not long after, Horatio and Delko followed Riaz to Brazil, where Horatio killed Riaz, avenging Marisol. Marisol returns in the season 10 premiere appearing to Horatio when he is agonizing of his wounds. He tells her he wants to go with her, but Marisol reminds him he must continue living because he has a life mission to complete, then Horatio comes to his feet and rescues Natalia. Through the episode, he continues remembering his wife and the happy moments he lived with her.
Nick Townsend (Rob Estes, season 5): Ex-husband of Natalia Boa Vista. Upon his release from prison, Nick re-entered Natalia's life as an employee of a crime-scene cleaning company who often worked crime scenes his ex-wife was assigned to process. Nick's treatment of Natalia following his parole consisted primarily of unwanted flirtation, which pushed Natalia into shoving him at a crime scene, an action Nick used as basis for a restraining order against her. Under the order, Natalia was forced to leave any crime scene Nick was sent to clean, which threatened her job. Nick subsequently agreed to drop the restraining order, provided Natalia treated him civilly from then on. Nick became a less-than-desirable presence on the job for both Natalia and Eric Delko, for whom Nick also took delight in causing discomfort due to Eric's prior romantic relationship with Natalia. Nick was murdered following a date with Maxine Valera, who'd shoved him to the floor in response to his unwanted advances and fled, thinking him dead. Though both Maxine and Natalia were suspected for the crime, Nick was in fact killed by a man whose wife had committed a murder Nick had worked that day. The man's name was Jeff Murdock and Lauren Sloan was his wife. Nick had taken Lauren's earring from the crime scene and was bludgeoned to death when he taunted Jeff and refused to return it.
Clavo Cruz (Gonzalo Menendez, seasons 2–3, 5): In season 2, Clavo started out as an arrogant criminal who killed a model with his Lamborghini to protect his brother Ramon, who had accidentally drowned the model's roommate (#201 – "Blood Brothers"). When the team tried to arrest Clavo, it was revealed that the brothers' father was General Antonio Cruz, an ambassador from the Baracas, an area which was under diplomatic immunity from the United States. Therefore, they could neither arrest Clavo nor could they use any of his possessions as evidence. His older brother (Ramon) was able to be arrested, as the woman he drowned was on Canadian soil (the Canadian Embassy), had Canadian blood, and because he flew the Bahamian flag in international waters, leaving him unprotected and arrestable in the Bahamas. Clavo reappears in season 3 after being traced to the murder of a woman who was found after being swallowed and then regurgitated from a boa constrictor (#315 – "Identity"). He continues to taunt Caine, using the line "We never close", a line Caine had spoken after arresting Ramon. A blood test of General Cruz, the alleged father of Ramon and Clavo, revealed that although Clavo and Ramon had the same mother, Dona Marta Cruz, they had different fathers, making Clavo an adoptive son of General Cruz. When Caine reveals Marta’s infidelity to the family, the General becomes infuriated. Caine then reminds the General that he can disown Clavo and thus rescind his immunity at any time; he does immediately, allowing the CSIs to arrest Clavo. In season 5, however, Clavo escapes custody after a cohort steals a rocket launcher from a crime scene and blows up the courthouse in which he was being arraigned (#514 – "No Man's Land"). He later lures Caine and Delko into a parking lot to find a hostage, who turns out not to be there. In the ensuing gun battle with his cohorts, Delko is nearly killed when a security guard shoots him in the head (Clavo offered him $100,000 to do so). In the next episode (#515 – "Man Down"), Clavo seeks revenge, killing his adoptive father in the consulate. Later on, Clavo's real father is revealed, and as it turns out, Clavo had smuggled illegal blood diamonds into Miami, and his escape from jail was intended to help his father sell them to underground dealers. One of the dealers is raided and shut down after the plain sight of illegal child labor by Natalia and Ryan. After being disowned by his biological father and having nothing to live for, Clavo returns to "duel" with Caine. Immediately after raising his gun at Caine, he is shot once in the chest by Caine, and dies.
Ron Saris (Kim Coates, seasons 6–7): Boyfriend and later ex-husband of Julia Winston. He was suspected by Horatio in an illegal-ammunition case, and married Julia Winston in "Going Ballistic" (the sixth-season finale). Julia double-crossed him for Caine in the season-seven premiere when he was planning to escape the United States by boat. He shot at Caine when Caine is revealed and ran; Horatio shot a fuel canister on the boat and blew it up, but Saris' body was never found. He was later revealed to have survived the explosion in "Chip/Tuck", where he was shown to have had some surgery on the left side of his face, which was burned by the explosion. He became a confidential informant for the Miami police, which ensured that Horatio and the rest of the teams could not arrest him for any crimes (as informants are given immunity), which was his intent.
Joseph Ratner (William Allen Young; seasons 3–5): A disgraced former Florida trial judge and enemy of Horatio Caine. In "After the Fall", he is discovered to have murdered a prostitute, but (thanks to legal maneuvering) he is able to get away with the crime. He appears later in season 4, releasing Caine's old enemy, Walter Dresden, from prison ("Under Suspicion") despite Horatio telling the judge that he would have blood on his hands. In the fifth season, he was charged with orchestrating the murder of his own daughter, but he did not believe her at the time because, in his mind, there was no way a teenage runaway could be related to him. Luckily, a DNA match later revealed the truth, and Ratner was eventually arrested in his own former chambers ("Death Eminent").
The Mala Noche is a multibranched gang which Horatio Caine once described as one of the most dangerous in the region and "Miami's new Mafia". First mentioned early in the fourth season, they would become a regular presence on the show for the next two years; many of the murder cases the team uncovered were carried out by one or more of the Mala Noche members. The Mala Noche was also responsible for the murder of Marisol Delko, Eric's sister and Horatio's new wife, on her wedding day. Ultimately, the gang would cease to be a viable threat in the sixth season after Horatio was extradited to Brazil and ultimately killed its remaining leadership (its original leader, Antonio Riaz, was killed in the fifth-season premiere as revenge for Marisol's death).
Walter Dresden (Damian Young, season 4): A significant enemy of Caine's. Dresden drove Caine out of his former career in the NYPD; he would appear in Miami ten years later, framing Caine for the murder of his (Caine's) girlfriend, Rachael Turner. He gets away with it, however, thanks to the help of Joseph Ratner ("Under Suspicion"), who rules that Dresden be released. He reappears several episodes later, targeting the daughter of two of his former victims, and his former foster home siblings. When he attempts to kill Caine with a shotgun, Caine shoots him in the shoulder. Walter Dresden is then arrested shortly afterwards, charged not only with attempted murder, but murder as well, due to the discovery of new evidence against him ("Skeletons"). Although Horatio learns that Dresden targeted his victims because his foster siblings allowed their foster father to brutally abuse him – his father would beat him with a belt and then lock him in a closet (one of his foster siblings tried to stop his father once and choked his father with the belt) – Caine tells Dresden he has no sympathy at all for him.
IAB Sergeant Rick Stetler (David Lee Smith, seasons 2–8): A disgraced former MDPD SOC Lieutenant and recurring nemesis of Horatio Caine and the Miami CSIs. He was briefly involved romantically with Yelina Salas, but she would eventually leave him—and the United States—for her husband in the season 3 finale. His harsh feelings toward Caine stemmed from bitterness over Horatio being promoted to lieutenant instead of him, believing Caine may have pulled in some "special favors" for the job. Horatio also suspected, during Stetler's relationship with Yelina, he may have been abusive, which is evident when she comes to work one day with a black eye. In season 3, episode "Crime Wave", Stetler later returns to warn Horatio against going after a corrupt city official, saying that he cannot protect him if Caine follows through. "Just like old times", the CSI replies (episode 517, "A Grizzly Murder"). Although Stetler often harasses Horatio, he has also been sympathetic and even helpful when he knew that he and the Crime Lab were being harassed/targeted by genuine bad guys. He tells Horatio to try to fight extradition when Horatio is arrested for the murder of Antonio Riaz. As of season eight (episode 8x02, "Hostile Takeover"), he was promoted to lieutenant in charge of SOC (SWAT team). In episode 821 ("Meltdown"), Stetler returns and attacks Wolfe and Walter Simmons for evidence tampering before being confronted by Horatio. In episode 823 ("Time Bomb"), it was revealed that Stetler himself was the one who had stolen the diamonds, and had attempted to frame Ryan for it. After being exposed, Ryan finally got the opportunity to arrest Stetler, which he did with great pleasure and also proceeded to walk through the Crime Lab with Stetler as all the personnel looked on, a repeat of the same event that Ryan had experienced upon Stetler arresting him at the beginning of the episode. It is also revealed that Stetler had been stealing cars from the impound lot for a two-year period. Stetler was the corrupt officer responsible for Rebecca Nevins dying in an explosion, though his intended victim was Eric Delko. After being arrested, Stetler is currently awaiting trial on these charges, including capital murder.
Monica West (Bellamy Young, season 4): A disgraced former Assistant Florida State Attorney. She was the one who planted Natalia Boa Vista as a mole within the MDPD's Crime Lab, hoping she would come up with evidence of corruption within the lab. However, when Natalia only brought back positive results on the lab, she got frustrated enough that she stole some money that the team seized in a raid on the Mala Noche gang. When her fiancee, Treasury Agent Peter Elliot, was looking over the money, she tipped off the FBI, causing the lab to be investigated. When Ryan Wolfe pointed out that the money was not taken from their lab, Calleigh figured it out and had Elliott confess to dereliction of duty. Calleigh made him get Monica to admit on tape that she was the one who took the money. She was then arrested.
FBI Agent Glen Cole (Mark Rolston, seasons 4,5): An FBI agent who headed an investigation into the MDPD Crime Lab in season 4. Cole returned in season 5, working on a case involving counterfeiting and the North Korean government (episodes 425, "One of Our Own", 503, "Death Pool 100"). After appearing less-than-likable in those turns, he was painted in a more positive light during his appearance in "Miami Confidential" (season 6), when he helps the CSIs investigate a junior FBI agent who turns out to be an accessory to murder.
WFOR-TV Newscaster Erica Sykes (Amy Laughlin, seasons 3–5, 9): An aggressive, ambitious young news reporter for Miami's CBS station WFOR-TV. Her antics are often described as crazy by the CSI team and they generally find her annoying, especially Ryan Wolfe. She targeted Ryan and broadcast him at close range, much to his annoyance, but in the end, the team used her tapes to find their suspect (episode 401, "From the Grave"). In the season 4 episode "Free Fall", Ryan warned her to stay away from two former prisoners after he suspected they were targets for murder. She refused to listen and got shot in the process. Erica revealed to Ryan that there was a mole in the lab in a special extended scene that was available on www.cbs.com after the episode "Urban Hellraisers" aired. She also helped Ryan in a case regarding abuse of eminent domain, with the government evicting people from their homes before turning the land over to a private developer (episode 505, "Death Eminent"). In a later episode, however, she put the life of Natalia's sister at risk by mentioning on the air that she is a victim in a kidnapping (episode 508, "Darkroom"). It is implied that CSI Boa Vista was jealous of Ryan and Erica's "closeness".
Secret Service Special Agent Peter Elliott (Michael B. Silver, seasons 2–5): Working in the Secret Service's Financial Crime Division, Agent Elliott had an obvious infatuation with Calleigh Duquesne that interested her, but she stopped short when she found out, after taking him to the hospital for a gunshot wound, that he was engaged to another woman. At the end of the season, it was revealed that his fiancée, Monica West, was the one that impunged the CSI lab and stole drug money seized in a raid; she caused the FBI to investigate, hoping that discrediting the lab would help her out politically. Elliot, wearing a wire, got her to confess, and she was arrested (episode 425, "One of Our Own").
Bob Keaton (Max Martini, seasons 2–3): Susie Keaton's abusive, drug-dealing husband. In "Big Brother", Horatio discovers that Bob's methamphetamine is the same batch as that used by Raymond Caine on the night of his alleged death. Despite his denials, Bob is convicted of Caine's murder and jailed. When he is released (episode 320, "Killer Date"), it is revealed that he is an undercover DEA agent and Caine's ex-partner. Bob confirms to Horatio that his brother is still alive. His involvement in the DEA investigation and his knowledge about the Caine case leads to his murder (episode 322, "Vengeance").
Assistant State Attorney Rebecca Nevins (Christina Chang, seasons 3, 6, and 8): Assistant Florida State Attorney. Rebecca was briefly romantically involved with Horatio Caine, but he broke it off when she made a deal with a criminal suspected of killing a cop, committing a series of robberies, and having a relationship with a 16-year-old girl who took part in his crimes. Nevins was not seen again after their breakup until season 6 (episodes 603 and 607, "Inside Out" and "Chain Reaction"), when she appeared as the assigned state prosecutor for Kyle Harmon on two occasions, driving a further wedge between Horatio and her. In "L.A.", Rebecca tells Horatio she has to suppress evidence submitted by CSI Jesse Cardoza due to his past history with a previous suspect in his former department. To help Horatio clear Cardoza's name, she sends Eric Delko (now the State Attorney's Forensic Expert) out with him to find the missing evidence from that previous case. In episode 823 ("Time Bomb"), she is killed in an explosion meant for Eric Delko, with whom she was meeting. They were both conducting an internal investigation of the lab after diamonds were stolen from an evidence locker.
Julia Winston (née Eberly) (Elizabeth Berkley, seasons 6–7): An ex-girlfriend of Horatio Caine's, from when he was working undercover, and Kyle Harmon's mother. Julia first appeared during the murder investigation of her wealthy current husband; she would serve as the show's antagonist for a time in the wake of Clavo Cruz's death, but it was eventually revealed that she was being forced into some evil actions by a psychotic ex-lover named Ron Saris. Ron would later marry Julia in the sixth-season finale, "Going Ballistic", shortly before the apparent murder of Horatio (Julia was initially one of the prime suspects in the shooting). Over time, Julia is proven to be a conflicted and mysterious woman. In the seventh-season episode, "Bombshell", it is revealed that she suffers from bipolar disorder, but had initially stopped taking her medication for it at Ron Saris' urging. Julia was committed to a psychiatric facility after nearly committing suicide late in the seventh season, and has not been seen since.
Special Agent Dennis Sackheim (Tom Hillmann, seasons 1, 2): An FBI agent first introduced in the crossover episode, "Cross Jurisdictions" who had a contemptuous working relationship with Horatio Caine. In their first scene together, Caine confronts Sackheim for meddling in a Miami-Dade crime that may have resulted in an unnecessary death. Later they are on the waterfront at night, assuming the killer is on the boat, when in fact it is one of the killer's victims. Sackheim orders his sharp shooter to "take him out!" and Caine intercedes at the last minute, saving the victim's life.