Born Andrew Armandoz Benavidez in Las Cruces, New Mexico, Pixley joined the U.S. Army after being charged with passing bad checks. His father Columbus Pixley said he had dropped out of high school and had never held a job. He served two years, mostly overseas. He was described as "slightly built" and "nervous" and as a transient and dishwasher. There was a previous warrant out for his arrest in his home town on a charge of larceny. He was accused and cleared of being in possession of a stolen car in Davenport, Washington, two weeks before the murders. He had been living in a trailer with two employees of the hotel where the murders took place, David Starling and Orval Edwards. Starling was described as having had prior knowledge of Pixley's violent tendencies.
On the night of August 5/6, 1964, Pixley broke into a room of the Wort Motor Hotel in Jackson, Wyoming, occupied by the family of Illinois Circuit Court Judge Robert McAuliffe, who were on vacation. McAuliffe and his wife were elsewhere in the hotel taking in a show. When they returned to their room, they found Pixley lying on the floor. He appeared to be drunk, but may have been feigning; McAuliffe said at the trial he had not smelled alcohol. McAuliffe grabbed Pixley and pinned him to the floor. Police officer James Jensen heard Mrs. McAuliffe screaming and rushed to the scene, where McAuliffe shouted "My God, this man has killed my babies."
Their older daughters, Debbie, 12, and Cindy, 8 lay dead in their beds. The girls had been sexually assaulted, Debbie had been bludgeoned with a rock, and Cindy beaten and strangled.
Initially, Pixley only told police "I didn't do it." Hotel employee Richard Southern testified that Pixley cited his Native American heritage in explaining why he "couldn't" have done such a thing. Later, Pixley asked to make a statement, and was examined using sodium pentothal interviews. He said he remembered drinking earlier in the evening, but could not remember entering the hotel or killing the girls. His court-appointed attorney, Robert Hufsmith, added that Pixley remembered being in the company of another person earlier that evening, but that his mind was "blank since he left that person."
Pixley was examined by Dr. William Karn, Jr. of the Wyoming State Hospital, who pronounced him sane, but an "incurable sociopath" at the trial, adding that "it meant a lot more to Pixley to kill the girls while they were awake." At this, Judge McAuliffe got up from his seat and attempted to assault Pixley before being restrained.
Pixley was tried and sentenced to death, laughing when the execution date was announced. Although an appeal was filed to change his sentence to life imprisonment, he said he did not want an appeal. He was executed in the Wyoming gas chamber on December 10, 1965. He took the longest time to die of any person ever executed in the Wyoming gas chamber.
According to genealogical research, Robert and Betty McAuliffe divorced sometime after the murders. McAuliffe remarried Charlotte Olivia Moon Branch and had a son, Jon David McAuliffe, born on 1/21/1974 in Chicago. He died April 1, 1998, of a heart attack. Betty McAuliffe died November 28, 2010. Susan McAuliffe married and had five children.
- "Slain Girls' Kin Returns From Wyoming", Chicago Tribune, August 10, 1964
- "Former Soldier Held in Deaths of Two Sisters", The Fredericksburg, Virginia Free Lance-Star, 8 August 1964.
- "Alleged killer of 2 girls changes jails", The Eugene Register-Guard, 9 August 1964
- "Ex-Soldier Held in Assault Deaths of 2 Sisters", The Miami News, 8 August 1964.
- "Father Testifies at Pixley Trial", Deseret News, 3 February 1965
- "2 Girls Slain, Judge Nabs Suspect", The Milwaukee Journal, 8 August 1964.
- "$250,000 suit filed against Wyoming hotel", The Bulletin (Bend, OR), 19 March 1966.
- "$250,000 suit filed against Wyoming hotel", The Bulletin (Bend, OR), 19 March 1966
- "Police Hold Youth in Killing of 2 Girls", The Pittsburgh Press, 8 August 1964
- "Pixley Facing Murder Charges in Wyoming", "The Bulletin (Bend, OR), 8 August 1964
- "Pixley held in slaying", "The Bulletin (Bend, OR), 11 August 1964
- "Sisters Together Forever", The Spokesman-Review, 15 August 1964
- Pixley Facing Murder Charges in Wyoming. In The Bend, Oregon Bulletin, August 8, 1964.
- "I'm an Indian--I couldn't have done that." Oregon Man Being Tried in Wyoming in the Eugene Register-Guard, February 3, 1965.
- Accused Murderer Says Memory Blank, in the Washington, NC Morning Star-News, August 8, 1964.
- Court Decision: Death For Pixley. In the Deseret News, February 4, 1965.
- "Oregon Man Sentenced To Death", Eugene Register-Guard, 4 February 1965
- "Appeal Prepared on Death Sentence", Eugene Register-Guard, 12 February 1965.
- Genealogical research on the McAuliffe-Dowd families Archived September 27, 2011, at the Wayback Machine., page found 2011-07-02.
- ["Archived copy". Archived from the original on 2011-09-27. Retrieved 2011-07-02. McAuliffe genealogy at City-Net, page found 2015-03-21.
- Obituary for Betty Jane McAuliffe, Chicago Tribune.