Keene became involved in selling marijuana as a teenager. In 1996, he was charged by the
FBI and the
DEA on a conspiracy charge. Prior to his sentencing, Keene did not cooperate with law enforcement according to his autobiography. He was sentenced to 10 years in prison. Approximately seven months into Keene's sentence, the FBI and prosecutors approached him with an arrangement that would allow Keene to reduce his prison sentence and expunge his record. Law enforcement had only found the remains of one of Hall's victims, 15-year-old Jessica Roach. Hall confessed to the murder, but prosecutors lacked strong physical evidence for the case. After Hall retracted his confession and his attorneys filed an appeal, the FBI feared Hall's possible release was imminent. However, if Keene succeeded in obtaining new incriminating evidence about Hall while in MCFP, the U.S. Attorney and FBI agreed to end Keene's sentence and
expunge his record. With the guidance and training by the FBI, a cover story was arranged for Keene as part of his undercover mission. He was transferred to the MCFP, where he gained Hall's trust. Hall allegedly admitted to specific details about many of his crimes and murders in graphic details to Keene that no one but the killer could have known. On one occasion, Keene witnessed Hall with a map that appeared to show the locations of his victims' remains, and Keene reported the information to his FBI contacts. The U.S. Attorney and FBI rewarded Keene's cooperation with early release and a clean record. == Media adaptations and books ==