Delayed 911 response leads to Brittany Zimmermann's death

The dispatcher who took the April 2 call from Brittany Zimmermann's phone shortly before she was murdered told investigators that she either didn't hear a scream or that "it didn't register as a scream."

The length of delay between the mishandled 911 call and when Madison police were sent to her West Doty Street apartment to find her brutally murdered haven't been made known to the public.

Investigators have however revealed in previously sealed court documents obtained by the Wisconsin State Journal that the delay time was 48 minutes.

Dane County has taken some harsh criticism from the public regarding the delay, and tough questions have been raised about whether a prompt response might have saved Zimmerman's life.

Police are still looking for her killer.

"We are working diligently on this case, have generated significant leads, and are making progress," said Joel De Spain of the Madison Police Department.

The police said they believe Zimmerman was attacked by a stranger. Her apartment door showed signs of forced entry.