MADISON, Wis. (WSAU) – A Marshfield native's murder remains unsolved two years after it happened.

Brittany Zimmermann was killed in her off-campus Madison apartment April 2, 2008. Police have not found her killer and are offering a $15,000 reward for an arrest.

Zimmermann was a pre-med student at the University of Wisconsin.

Zimmermann's mother Jean wants answers in her daughter's case.

“We wait for the phone to ring to give us the answers we deserve and the justice that Brittany deserves – and they have not come,” she told WIBA Radio in Madison.

“To us that is unacceptable - we have to know what happened. We have to know who did it.”

Zimmermann's fiance found her stabbed to death but was ruled out early as a suspect.

“We wish that things could have been different every day but they can't,” Jean Zimmermann said. “We have to find who did this.”

Thanks for help WIBA-AM, Madison