A fellow inmate who acted as a suicide-watch "companion" for Jeffrey Epstein has said he is convinced the paedophile financier took his own life, having witnessed his mental decline in the days before his death. William "Dollar Bill" Mersey, speaking in a new BBC Panorama documentary, said Epstein appeared "defeated" during their final conversation, recalling him sitting on the floor of his cell eating chicken from a container and offering to put money on Mersey's prison account, which Mersey now believes was a farewell gesture. The account adds a first-hand voice to the long-running debate over Epstein's death, which was officially ruled a suicide but has since attracted numerous unsubstantiated conspiracy theories.

Mersey was at the Metropolitan Correctional Center in New York between January and November 2019, and spent an estimated 15 to 20 hours talking with Epstein as part of an inmate companion programme, which required four hours of training before prisoners could observe fellow inmates on suicide watch. This made him one of the few people with regular direct contact with Epstein besides prison staff and his lawyers. Epstein was found dead in his cell in August 2019 while awaiting trial on sex trafficking charges, weeks after an earlier suicide attempt had seen him moved to the jail's special suicide watch wing; his death was ruled a suicide by the New York medical examiner after the Bureau of Prisons initially called it an "apparent suicide".