(Photo by Jude Joffe-Block - KJZZ)

Paul Penzone is a former Phoenix police sergeant.

Paul Atkinson/KJZZ

Joe Arpaio

KJZZ's Jimmy Jenkins breaks down the latest development in the race for the Maricopa County Sheriff's office.

Thursday, Paul Penzone announced he is suing Arpaio for defamation for running an ad accusing Penzone of abusing his ex-wife.

"There's never been a time in my life where I've ever hurt, harmed any woman or child, including my former wife," Penzone said. "So for someone to take advantage of a personal issue during a difficult time when two people went through a divorce and emotions were involved, but no violence was truly involved— to try and take advantage of that for their own political gain, I find to be one of the most unethical and irresponsible things to do."

Kory Langhofer, counsel for the Arpaio campaign, said the sheriff has every right to dig into Penzone's background through public records.