Nancy Cooper's affair detailed in defense testimony

But John Pearson said during Brad Cooper's first-degree murder trial that his interviews with Cary police were otherwise complete and honest.

Full video: Day 33 trial testimony

"The only thing that I was holding back for privacy and protection of my children was that indiscretion that Nancy and I had after the Halloween party in 2005," Pearson said.

Brad Cooper, 37, is accused of strangling his wife in the early morning of July 12, 2008, and dumping her body in a drainage ditch several miles from their home.

Defense attorneys have said that Nancy Cooper went jogging that day and never returned home.

Pearson's testimony was part of defense attorneys' attempts to discredit Cary police investigators' work in the case.

They have accused police of ignoring witnesses and evidence to support their "Brad-did-it" theory, as well as looking at others who might have had a motive to kill Nancy Cooper.

Police never asked Pearson for a DNA sample, never searched his home and never asked if he was the father of the Coopers' youngest daughter, Katie, defense attorney Howard Kurtz said Tuesday.

In his initial interview with police, Pearson said he wasn't very close to Nancy Cooper but was more forthcoming in a second interview when pressed by police about the nature of their relationship.

Pearson said he remembered walking Nancy Cooper home from a Halloween party in October 2005, while Brad Cooper was out of town, and that she invited him inside.

“She began taking her clothes off. I took my clothes off, and we, I believe, started to have sex," Pearson said, adding that his memory was vague because he was intoxicated that night. "My memory is that we stopped and got dressed and decided to never speak about it again."

But they did. Katie Cooper was born approximately nine months later, raising questions about the child's paternity.

"I asked, 'Is there anything we should worry about here?'" Pearson said. "She said, ‘absolutely not,' and that was the only time we ever talked about it."

Pearson said he never had any romantic feelings for Nancy Cooper and that the two lost touch in 2006. He said he didn't really talk to her again until May 2008, when she called him "out of the blue" about a lawsuit his ex-wife had filed against Heather Metour, a woman with whom Pearson said he had been having an affair for several years.

The two met for coffee and talked a few other times over the next two months, Pearson said.

On cross-examination, Pearson said that he became worried months later when he found out about concerns that he might have been involved in Nancy Cooper's death.

"It was brought up by the defense that I was an alternate theory," Pearson said. "I became alarmed."

Scott Heider, a friend of Brad and Nancy Cooper and Metour's ex-husband, also testified Tuesday that Brad Cooper was always "politically correct" and watched what he said in public.

"He never aired his dirty laundry. He was respectful," Heider said. "He was calm. He never said anything inappropriate in public."

Witnesses have testified that the Cooper marriage was in trouble in 2008 because of an affair Brad Cooper admitted to having with Heider's ex-wife in 2005 and because of money.

Tensions between the two heightened in the week prior to Nancy Cooper's death, and witnesses said she fussed at her husband at a neighborhood barbecue the night before she died.

But Heider described the marriage as being "typical" and "standard" in 2006, when the two couples spent a significant amount of time together.

He said he couldn't recall the couple raising their voices to one another, and he said he never had any reason to believe that Nancy Cooper was afraid of her husband or that Brad Cooper was violent.

"He was an introvert," Heider said. "Quiet. Reserved. He kept his thoughts to himself."

Nancy Cooper, on the other hand was "gregarious" and "sociable" with a tendency of telling colorful stories that friends referred to as "nannerisms" – "Nancy's version of a story," Heider said, "very colorful – just airy and light and her version of it."