Details of the investigation into the April 2 slaying of UW-Madison student Brittany Zimmermann — which police, prosecutors and county officials have long fought to keep under wraps — are now public because a court order sealing search warrants in the case expired.

A Wisconsin State Journal reporter then asked the Dane County clerk of courts office to unseal the warrants.

In Wisconsin, police must file a return with the court within 48 hours of executing a search warrant.

If police or other authorities want to seal a search warrant, the return, and an accompanying affidavit that explains the reason police want to conduct the search, they must convince a judge there is sufficient cause to keep the documents out of public view for a specified number of days.

In the Zimmermann case, police and prosecutors have maintained that releasing details of the homicide could jeopardize the search for her killer.

"This office and police start with the premise that investigative details shouldn't be released to anyone who doesn't have the need to know them," said Dane County District Attorney Brian Blanchard.

But, Blanchard said, "Under Wisconsin law, we can't keep investigative secrets forever."

He said an "oversight" kept police and prosecutors from asking a judge to keep the documents in the Zimmermann case sealed.