NEW YORK (CNN)
-- Brittany Zimmerman, a 21-year-old college student who wanted to be a doctor, called 911 as she was being attacked by a stranger, police say.
Brittany Zimmerman's screams and struggle for her life were captured by a 911 tape.
But the police did not come for 48 minutes. By that time, Zimmerman was dead. Her fiance found her body.
Although the dispatcher claimed later to have heard nothing, the 911 tape captured screams, gasps and what sounds like a struggle, according to the court documents.
Spring was in the air when college student Zimmerman returned April 2 from classes at the University of Wisconsin to the off-campus apartment she shared with her fiance, Jordan Gonnering.
He was out when she arrived home. He discovered her body when he returned.
Zimmerman had been stabbed multiple times in her chest, near her heart. She'd also been beaten and strangled, according to warrants released recently. Watch an update on the case »
Zimmerman managed to call 911 at 12:20 p.m. The call was taken by the Dane County 911 center and an internal investigation revealed the dispatcher did not hear any sounds that would signal an emergency.
Because of that, police were not sent to the apartment until 48 minutes after Zimmerman made the call. Her fiance was already there.