A man whose confession helped free a death row inmate but who later recanted has filed a $40 million lawsuit against Northwestern University and a professor he alleges conspired to frame him for a double slaying.

Alstory Simon alleges shoddy oversight by Northwestern allowed former professor David Protess, private investigator Paul Ciolino and attorney Jack Rimland to conspire to frame him for the 1982 killings.

His videotaped confession led authorities to free Anthony Porter less than 48 hours before his scheduled execution in 1999.

The 64-year-old Simon spent nearly 15 years in prison before he was cleared by Cook County prosecutors in October.

Northwestern spokesman Alan K. Cubbage denied any wrongdoing.

Ciolino calls the lawsuit frivolous. Protess and Rimland did not immediately respond to calls seeking comment.