MADISON, Wis. -- Dane County Executive Kathleen Falk on Thursday dismissed a newly released e-mail by the dispatcher who took a call from a University of Wisconsin-Madison student's cell phone about the time she was being killed.

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In the e-mail sent on May 3, a month after Brittany Zimmermann's April 2 slaying, Rita Gahagan criticized Dane County's 911 Center. Gahagan sent the e-mail to Joe Norwick, who has since resigned as the center's director.

Gahagan suggested that in trying to explain alleged errors in handling Zimmermann's call, Norwick "could mention the failings of the new telephone system and the cheap headsets and the 20-year-old connections they plug into."

On Thursday, county officials put the focus on "human error" instead of any possible equipment problems, countering the assertion by Gahagan.

"Through several interviews with the dispatcher and reviews of other calls handled the day of the incident, the 911 Center investigation found the equipment worked properly. As reflected in recently released documents, the dispatcher did not raise questions or concerns about equipment during any of the three interviews with 911 management investigating the incident," the Dane County 911 center said in a statement.

The Dane County executive's office said the 911 center installed a new $500,000 telephone system in 2006 and new connections were installed in consoles in 2002. County officials said that after careful examination in April, neither was determined to have affected the call-taker's performance with the incident.

County officials also said Gahagan never requested a new headset, which are available at any time.

"They have a variety (of headsets) to choose from, and I think they're high quality equipment and they're well maintained and extra parts and service are available 24 hours a day," said Tom Hanrahan, of the 911 Center's support services.

Falk on Thursday called the 911 equipment "top of the line" and said that, despite training, "human error" happens.

"I think we just had a really frustrated, sad employee who wrote an e-mail a month after being under a lot of stress, and I can certainly appreciate that," Falk said.

Gahagan's e-mail also criticized the county for mixing up two other calls with her from Zimmermann.

"Someone could apologize for the fact that two calls that had nothing to do with each other were mistakenly taped as being related, making me think for a week and a half that I had spoken with the murderers," Gahagan wrote in the e-mail.

Gahagan's disciplinary review will wrap up by the end of the month. There was no comment from her union Thursday. Union representatives simply said that she was a highly competent dispatcher who heard no signs of distress during Zimmermann's call.

Following the court-ordered release of the e-mails, Nancy Mistele, a candidate for Dane County executive, released a statement.

"Another day, another tragic revelation about Kathleen Falk's failed leadership at the 911 Center. The county executive’s efforts to shift blame and silence criticism are shocking, and show she cannot be trusted to fix the 911 Center. As county executive, it will be my top priority to ensure our dispatchers and emergency personnel have every tool they need to do their jobs and keep our families safe," Mistele said in the statement.

Falk's campaign issued a response to Mistele's statement Thursday.

"As usual Nancy didn't bother to get her facts straight. The equipment worked and it is up to date. On the day she announced her candidacy Nancy accused Kathleen of being responsible for two deaths. Nancy's over-the-top posturing is shameful. These issues are too important to leave to Nancy Mistele, who is more interested in issuing press releases than in learning the facts," Melissa Mulliken, Falk's campaign manager, said in a statement.

The stabbing death of Zimmermann, a UW-Madison student from Marshfield, remains unsolved.