A former inmate who was Jeffrey Epstein‘s suicide-watch companion in a New York jail says the convicted pedophile definitely killed himself … telling TMZ the guy in the cell next to Epstein heard him ripping up bedsheets to hang himself.

Bill Mersey — who was locked up with Epstein back in the day at the since-shuttered Metropolitan Correctional Center — joined us on “TMZ Live” Thursday, and we asked him about the alleged Epstein suicide note, which wasjust released.

Bill spent hours talking to Epstein in lockup and says he watched Epstein lose all hope after being denied bail. He also says Epstein worried about what life in prison would look like and how he could stay safe from other inmates, particularly Black people.

While some folks aren’t convinced Epstein really killed himself, and doubt the authenticity of the note, Bill says he’s 99.9% sure this wasn’t murder … telling us why a conspiracy to kill Epstein in jail would be extremely difficult to pull off.

Bill says bedsheets and towels were easy to come by at MCC … and a guy in the next cell over on Epstein’s final night alive overheard him tearing up sheets. Plus, Bill says the guy swears no one came to their floor.

The official narrative is Epstein hanged himself by his neck while awaiting trial on sex trafficking charges in 2019 … and Bill’s buying it, based on his jail experience with Epstein.