MADISON, Wis. -

A federal judge has allowed an amended civil rights lawsuit filed by a man exonerated in a 1980 sexual assault and strangulation to proceed.

It's the third time Ralph Armstrong has filed the lawsuit in U.S. District Court in Madison. Armstrong was convicted in the death of University of Wisconsin-Madison student Charise Kamps -- a conviction that was overturned in 2009.

The State Journal reported Judge Barbara Crabb has allowed Strong's latest lawsuit to go forward on claims that prosecutors lost evidence that could have benefited him at trial in 1980 and that prosecutors, police and crime lab employees destroyed DNA evidence before he was to be re-tried.

Crabb won't allow Armstrong to pursue other claims, including witness tampering and suppression of an alleged confession by Armstrong's brother.