MADISON, Wis. -- The 911 call received from the cell phone of a University of Wisconsin-Madison student slain last month may contain additional evidence that hasn't been explored yet, which has police considering whether a forensic analysis of the call would yield more information.
Earlier this month, officials said a 911 call had been received from the cell phone of Brittany Zimmermann, who was slain in her downtown apartment April 2.
Madison Police Chief Noble Wray said evidence on the call should have been heard by the 911 dispatcher who handled the call and that should have prompted her to send police. Dane County Executive Kathleen Falk said the call contained "significant sounds" that were not heard by the dispatcher.
Joe Norwick, director of the Dane County Public Safety Communications Center, originally said the dispatcher who took the call asked several times if there was an emergency but got no response.
Documents that have been released have identified the dispatcher who handled the call as Rita Gahagan. Attempts to reach her Friday were not successful.
The Journal Sentinel requested a copy of the call to 911 from Zimmermann's phone. Dane County officials and the Police Department denied that request.
In a letter, Madison police Capt. Carl Gloede, the department's records custodian, said that while there is strong public interest in making sure law enforcement officials are conducting a thorough investigation, the public interest in catching Zimmermann's killer could be undermined if the call were to be released.
The Journal Sentinel and three other media organizations have sued Dane County and the City of Madison for withholding public records, including the tape of the 911 call.
The lawsuit says that the 911 system is maintained at public expense for the public's benefit, and the system's effectiveness has been called into question by developments in the Zimmermann case.
Police are consulting with two federal law enforcement agencies about "conducting sophisticated forensic analysis" of the call, Gloede said.
"This forensic analysis may yield additional evidentiary material," he wrote. "Thus, at this time, the full investigative and evidentiary value of this recording is not fully known to the investigators."
In an interview, Gloede said results of the analysis could include voice patterns, background noises or sounds that might be undecipherable to normal hearing.
Also Friday, Dane County launched dane911.com, a Web site with information about how its 911 center works.