Dane County's 911 Center director admitted late Thursday that his agency made a mistake in fumbling a call from Brittany Zimmermann's cell phone at about the time she was killed on April 2.

But after a month of internal investigation, the dispatcher who hung up on the call, after hearing nothing, remains on the job without disciplinary action, and the agency has made no changes in policy, training or procedure, director Joseph Norwick acknowledged.

An internal investigation has begun, and dispatchers were reminded of the policy to call back when a 911 caller hangs up or is disconnected, he said.

"Hindsight is a great thing," Norwick said after a long day of fielding questions and criticism.

Zimmermann's body was found in her apartment on West Doty Street in the middle of the day, not long after she returned home from class. Someone forced entry into her building and she died of "a complexity of traumatic injuries," the coroner said. An official familiar with the investigation said she was stabbed.

Police say they don't have any suspects, that Zimmermann had no enemies and that the killer may still be in Madison. Her killing and four other unsolved homicides in the past 10 months have heightened public safety concerns.

Investigators have kept almost everything about the killing cloaked in secrecy, saying that to do otherwise would make solving the case more difficult.

The gaffe at the 911 center, disclosed Thursday by the weekly newspaper Isthmus, prompted a news conference by Norwick and by Madison Police Chief Noble Wray, but many questions remain unanswered.

Norwick denied the 911 Center has tried to cover up the operator's oversight, despite the month that has passed since Zimmermann was killed.

"I don't think there is anything to apologize for at this time," he said.

Dane County Executive Kathleen Falk wouldn't provide any information about the mishandled call, saying it was a personnel matter and it remains under investigation.

The center has a $5.5 million annual budget and 59 dispatchers who handle about 174,000 calls each year.

Madison police asked the 911 center about the call from Zimmermann's phone shortly after the homicide, when detectives examined phone records.

Wray said he immediately asked the county to investigate why the call was mishandled.

Wray said he didn't know whether dispatching a police officer would have saved Zimmermann's life.

He said he will meet with 911 officials. "Just like you, I am asking questions," he told reporters.

Police policy

The body of Zimmermann, 21, of Marshfield was found by her fiancee around 1 p.m.

Norwick and Wray refused to say what time the call from Zimmermann's phone was made. Norwick also wouldn't say how long the line was open before the operator hung up.

Wray asserted there was some sort of "evidence contained in the call," but Norwick maintains the dispatcher heard nothing.

In a 2007 memorandum to the dispatch center, the Madison Police Department said dispatchers should not notify police for routine 911 cellular hang-ups.

But "if the dispatcher has reason to believe that police services are needed, appropriate police resources shall be dispatched to the area the cell phone call was made from," the memo said.

Norwick said the dispatcher got busy with other calls and forgot to call back to Zimmermann's phone.

"Other 911 calls were waiting," he said.

"But had we called it back and got the same result — or if we got somebody's voice mail — we probably wouldn't have sent anybody anyway," Norwick said.

The center may be able to determine the origin of a cell call within a city block or several miles, he said.

Evidence ignored

Norwick said Madison police told the call center not to routinely dispatch officers after cell-phone "hang-up calls" because of the difficulty of finding addresses.

Wray, however, said the 911 center ignored evidence in the call "which should have resulted in a Madison police officer being dispatched."

The county dispatch center has sufficient technology to track cell-phone locations, Wray said.

Falk said the 911 Center uses the latest technology, but the level of precision in tracing cell phones can vary.

When a 911 hang-up call is from a phone on the land-line system, Norwick said, dispatchers can see the address on a display and police are automatically dispatched.

Cell phone calls don't display the caller's address on 911 equipment.

Accidental calls

Norwick said the 911 center gets many accidental or erroneous phone calls.

On the day Zimmermann was killed, 115 hang-up calls were received, and 83 of them were from cell phones, he said.

"These calls can range from children playing with phones, buttons inadvertently bumped on phones left in coat pockets or purses, or crime victims looking for help," Norwick said.

Norwick said his agency has notified Madison police several times that it is willing and able to dispatch police when these kind of cell calls come in, but Madison police have declined the offer. Police say the department's stance is outlined in the 2007 memo.

Under current policy, Norwick said, if dispatchers answer a 911 call and can't determine whether it's an emergency, the dispatcher calls the number back.

'Passing blame'

Dane County Board Chairman Scott McDonell said he didn't have enough information to comment on the actions of the 911 staff.

"We need to fix any problems that exist, and we will," McDonell said.

He also said he was upset that Thursday's news was playing out like an interdepartmental battle, and a distraction from solving a crime that took place in his district.

"It seems like people's energies are focused on passing blame instead of trying to find the killer," McDonell said. "Nothing is going to change what happened on that day and how we're going to catch someone who is on the loose."

Patricia Simms can be contacted at psimms@madison.com or 608-252-6492. Matt DeFour at mdefour@madison.com or 608-252-6144.