Peacock's Devil in Disguise followed John Wayne Gacy's crimes - and execution - but what details did the show change? Gacy was a serial killer and sex offender who raped, tortured and murdered dozens of young men and boys. After he was convicted, he was sentenced to death and died by lethal injection in 1994. The limited series, which premiered on Thursday, October 16, made an effort to focus on Gacy's victims - something other shows centered around notorious murderers have been chastised for allegedly ignoring.