HARRISBURG, Pa. - The former Penn State graduate assistant whose testimony helped convict Jerry Sandusky on child sex abuse charges is now suing the university.

Mike McQueary claims the school ruined his reputation and fired him for his cooperation in the investigation against the former assistant football coach.

According to the defamation lawsuit, McQueary is seeking $4 million, which is equivalent to a life-long salary as a football coach at Penn State. He lost his job in July after testifying that he saw Sandusky in a locker room shower with a young boy in 2001.

Penn State has declined to comment on the suit.