Later that evening, Gay was arrested outside a camper in Silver Springs. Investigators went there after friends found Russell's body wrapped in a green sleeping bag.
The Marion County Sheriff’s Office also released a 160-page report and recorded interviews with Russell’s friends and family.
Deputies said Gay admitted he killed Russell when she woke up around 6 a.m. June 2 and caught him trying to steal money and prescription Fentanyl patches.
He told investigators he first tried smothering her with a pillow, then beat her with a large flashlight before finally using a telephone cord.
The state attorney's office said it has video of the confession and has turned it over to the defense.