Photo courtesy of NPR

(Harrisburg) -- A former Penn State assistant football coach who testified in the Jerry Sandusky child sex abuse case is disputing the university's assertion that he was fired as part of a routine changing of the guard under a new head football coach. 

Former assistant coach Mike McQueary has filed a whistleblower and defamation lawsuit against Penn State.

The university has always maintained that new head coach Bill O'Brien simply didn't rehire McQueary after his contract expired at the end of June 2012

But McQueary filed a response Friday in Centre County court saying he was employed "with no specified ending date."

And he says even if the contract ended last year, "strict proof" is required of when the decision to terminate him was made.