Find out what went wrong and fix it.

Those are the instructions the Madison community should give to Dane County 's 911 Center and the Madison Police Department in the aftermath of Thursday 's revelations about the day UW-Madison student Brittany Zimmermann was murdered.

Conclusions should remain limited at this point, because much information about the month-old murder case remains unknown to the public. That 's because the authorities are not telling us everything.

What we do know about the handling of a 911 call from Zimmermann 's cell phone is enough not only to cause outrage but also to threaten the public 's faith that a call to 911 will bring help.

The call from Zimmermann 's phone was made around the time the 21-year-old woman was murdered in her Downtown apartment April 2.

Yet, no officer was dispatched.

Thursday the 911 Center and the Madison police engaged in some veiled finger-pointing.

The 911 Center said the operator heard no voice on the line and had other calls to take. But the police said there was enough evidence on the call to warrant the dispatch of an officer.

Regardless, the 911 Center 's policy was to call Zimmermann 's number back to try to determine the facts.

That call was never made.

For this, 911 Center Director Joe Norwick had no apology.

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

Norwick is wrong. There is plenty to apologize for.

Apologies, however, are not sufficient. The Madison area cannot be reassured about the 911 system until a full evaluation is completed to determine why the policy failed to produce a call-back to Zimmermann 's number.

Once that determination is made, changes should be implemented.

County Executive Kathleen Falk and Madison Mayor Dave Cieslewicz should provide the leadership and oversight to make sure the 911 Center and Police Department understand the gravity of the mistake and follow through with repairs.

There are excuses for what went wrong. But the result is nonetheless inexcusable.

Authorities cannot allow it to happen again.