MADISON, Wis. (AP) -- Madison's police chief says an officer should have been dispatched to investigate a 911 call from a college student shortly before she was murdered.

Police Chief Noble Wray says the call from Brittany Zimmermann's cell phone contains evidence and should have been enough for a dispatcher to ask his department to send an officer.

He says the Dane County 911 Center never notified his agency and no officer was sent. He says he's concerned about the way the call was handled and asked for an internal investigation shortly after the April 2 murder of the University of Wisconsin-Madison student.

Zimmermann was murdered in her apartment while she was home alone. Police continue to search for her killer.