DETROIT -

A Detroit hit man in prison for eight slayings has signed an extraordinary confession to try to clear a young man who is locked up for four other murders.

The sworn affidavit by Vincent Smothers is his most formal, detailed explanation of what happened in September 2007. He says he and an accomplice ambushed and killed four people at a Detroit drug house -- not Davontae Sanford.

Sanford's lawyer is asking the Michigan appeals court to order a judge to hear Smothers' testimony. Wayne County Judge Brian Sullivan said no in February and has refused to throw out Sanford's conviction.

Sanford pleaded guilty at age 15 but says his confession was false. Smothers told police in 2008 they had the wrong guy, but authorities ignored him. He's never been charged.