Brittany Zimmermann, the UW-Madison junior killed in her apartment last month, called 911 before she died, officials confirmed Thursday.

Dane County 911 Center Director Joe Norwick said at a news conference Thursday Zimmermann made the call from her cell phone but was disconnected after a dispatcher did not hear anything and mistook Zimmermann’s call for a “hang up.”

Madison Police Chief Noble Wray said police were not notified of the call but should have been summoned to Zimmermann’s residence by the dispatch center.

“It would be accurate to state that there is evidence contained in the call, which should have resulted in a Madison police officer being dispatched,” Wray said at a news conference.

According to Wray, dispatching an officer would have been consistent with both MPD policy and national 911 standards. Both police and Norwick said audio from Zimmermann’s call, content of the call or time the call was placed will not be released at this time to avoid compromising the ongoing homicide investigation.

After receiving Zimmermann’s call, Norwick said the dispatcher answered a second call, which was determined to be an actual hang up. The dispatcher then called the second number back, confirmed it was an accidental call and proceeded to answer a third 911 call regarding an unwanted person in a residence.

According to Norwick, Dane County 911 Center policy instructs dispatchers to call back hang-up calls, from both landline and cellphone calls, to verify there is no emergency.

If a hang-up call is made from a landline, the 911 Center automatically dispatches police to the residence to determine if an emergency occurred.

“The technology of landline telephones allows [us] to get a reading for the address. That’s not so in cell-phone technology today,” Norwick said.

On the day of Zimmermann’s death, the 911 Center received 115 hang-up calls, 83 of which came from cell phones. Wray recommended the 911 Center conduct an internal investigation shortly after the homicide to determine what happened in the case of Zimmermann’s call to 911.

Norwick said the unnamed dispatcher who fielded Zimmermann’s call was not disciplined and continued to work after the event.

“The dispatcher is a competent, caring person and a long-standing employee with a good record,” he said.

Zimmermann’s fiancé discovered her body April 2 in a West Doty Street apartment the two shared. Her killer remains at large, but police said the homicide investigation is still active.