MADISON, Wis. (AP) -- The parents of a slain University of Wisconsin-Madison student want authorities to release the 911 call she made before she was murdered.

Kevin and Jean Zimmermann want to intervene in a lawsuit brought by media groups seeking audio of the call from Brittany Zimmermann's cell phone.

Zimmermann was murdered in her apartment April 2, and police are searching for her killer. Authorities say she called 911, but a dispatcher apparently heard nothing and hung up.

Police say the call contains evidence and should have prompted a dispatch.

Her parents say they requested the call but were denied because authorities say it would hurt their investigation. The Zimmermanns say they would abide by any confidentiality order imposed by the court.