Just before he killed himself, Jeffrey Epstein tried but failed to connect with -- of all people -- fellow pedophile Larry Nassar ... according to a new report.
The Associated Press filed a Freedom of Information Act request with the federal Bureau of Prisons and obtained 4,000 documents, detailing Epstein's life and declining mental health inside the Metropolitan Correctional Center in NYC.
Epstein's attempt to reach out to Nassar -- who was also locked up in federal prison -- was part of the avalanche of docs released Thursday by the AP.
The records state Epstein wrote a letter to Nassar and mailed it to him while the two were incarcerated in separate facilities. The letter was apparently received by Nassar's prison, but correction officials sent the note back to Epstein, yet he never saw it again.
The docs say Epstein's letter was found unopened in the mail room of his prison weeks after he hanged himself in his cell in August 2019. The words, "Return To Sender," were stamped across the envelope.
A prison official wrote in an email to a colleague ... "I am not sure if I should open [the letter] or should we hand it over to anyone?”
The contents of the letter were not publicly disclosed.
As we reported, Epstein was facing decades behind bars before his suicide after the feds indicted him on charges of sex trafficking minors.
Nassar - a former renowned US Gymnastics doctor -- is currently serving two life sentences after his convictions in state and federal court for sexually abusing 150 women and girls over several decades. Among his victims were the nation's foremost Olympic gymnasts.