John Leo “Juan” Flynn was born on November 9, 1943 in Panama. After serving in the infantry in Vietnam in 1968 he went to work at Spahn Ranch for $2.50 a week plus room and board. Like Steve Grogan, Juan had already been working at Spahn Ranch when the Manson gang arrived. He was employed as a “ranch hand” and “manure shoveler” and spent time with the Manson family while they lived there. Although not officially a family member, he participated in turning stolen cars into dune buggies, which became a regular source of income for the family. In return, Manson would often allow Flynn to have sex with some of the female family members.

During the Tate and LaBianca murder trial, Flynn was a key witness and testified that Charles Manson had confided in him and admitted he was doing all the killings and that Manson had bragged about killing as many as 35 people.