Nancy Cooper's twin details sister's troubled marriage

Krista Lister said she was at a baseball game in Toronto on the afternoon of July 12, 2008, when she received two calls from friends wanting to know if she had heard from Nancy Cooper.

Full video: Day 18 trial testimony

Around 3:30 p.m. that day, she said, she called her sister's home in Cary. Brad Cooper answered.

"(I asked) if Nan was there, and he said, 'No,'" a tearful Lister recalled. "I said, 'What have you done to her?' And I hung up."

Brad Cooper, 37, is accused of killing his wife, Nancy Cooper, 34, and dumping her body in an undeveloped subdivision 3 miles from the Coopers' home. He contends that she went jogging that morning and never returned home.

But when Brad Cooper found out preliminary details of a separation agreement outlining his financial obligations to Nancy Cooper and his daughters," he freaked out," Lister said.

"He just halted everything," she said. "(Nancy) was lost. All we knew was that she had to get the separation agreement done and that she needed to get out of the house, but she didn't know what she was going to do."

The relationship was rocky and tense, Lister said, adding that she heard the couple yell, scream and argue over money several times during a visit in early 2008.

Unable to obtain a visa to work legally in the U.S., Nancy Cooper was financially dependent on her husband, witnesses have said, after he cut her off from their bank account and credit cards, allotting her $300 a week for groceries and gasoline.

Lister said that, when she offered to give her sister money, Nancy Cooper begged her not to, telling her "that her life would be hell" and that "she would have to deal with the repercussions."

"It had gotten really bad and she needed out," Lister said of the Coopers' relationship. "She was looking for any help, any idea. She just needed out."

Monday marked the 18th day of testimony for the state, which contends that Brad Cooper, killed his wife sometime after she returned from a neighborhood party around 12:30 a.m. on July 12, 2008.

Wes Watson, an entomologist for the North Carolina Program for Forensic Sciences, testified Monday that fly larvae on Nancy Cooper's body indicated she had been dead anywhere from 68 to 72 hours before her body was found, putting her time of death sometime between 1 a.m. and 6 a.m. on July 12, 2008.

On cross-examination, he said he wasn't completely confident in the results because he had so few samples with which to work. The larvae weren't properly preserved, he said, and all but 12 of the living specimen died before he had a chance to examine them.

Heather Hanna, a geochemist with the North Carolina Geological Survey, also testified that she found white mica on a pair of Brad Cooper's shoes that was similar to white mica at the site where investigators recovered Nancy Cooper's body.

But she said she could not reach a conclusion as to whether the two samples had the same chemical composition.

Defense attorneys have accused Cary police of focusing solely on their client as a suspect, tampering with evidence and ignoring other information that could have helped find Nancy Cooper’s killer.

They questioned Cary police officer David Hazelzet on Monday about why he did not take photos or collect pieces of straw he observed on the front hall rug of the Cooper home on July 15, 2008, the day after Nancy Cooper's body was recovered.

Hazelzet testified Friday that the straw on the rug caught his attention because it was similar to straw he saw covering grass at the site where Nancy Cooper was found dead.

He said that he never seized it because a search warrant hadn't been issued and he had no legal authority to do so. When he went back inside the residence later that day, he didn't look for it again, he said.

No straw has been entered into evidence, so far, and it's unclear whether it was ever recovered from the home.