WFAA-TV

Investigative reporter Brett Shipp attempts to speak with Collin County prosecutor Kerrie Walker.

COLLIN COUNTY — The woman at the center of a News 8 investigation has resigned.

Kerrie Walker was the chief Collin County prosecutor handling a drunk driving case that witnesses and police said was rock solid.

Walker abruptly took over the case from a subordinate, dismissed the witnesses and canceled the jury trial.

The defendant was then found not guilty.

Collin County District Attorney John Roach said that Walker's actions — and perhaps those of another prosecutor — appear to violate county policies.

Roach's investigation continues.

Kerrie Walker had been a prosecutor in the county's misdemeanor trial division since 2008. According to her biography on the district attorney's Web site, she was a Frisco police officer before attending law school at Texas Wesleyan.