Raleigh, N.C. — Nancy Cooper told a friend that she slept in her jeans with her keys in her pocket in the few months preceding her death, a friend said Tuesday in the first-degree murder trial of her husband, Brad Cooper.

"She just said that maybe some day she would have to get out fast," Theresa Hackeling testified.

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She also kept important documents locked in her car, including her and her children's passports, paperwork from lawyers, her wallet and phone as she sought a separation from her husband.

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

During cross-examination, Hackeling said she did not know that Nancy Cooper had a tendency to exaggerate, and that she had no reason not to believe her friend.

Witnesses, including Hackeling, have testified that the couple's marriage had been troubled because of finances and Brad Cooper's admission to an affair with a friend of Nancy Cooper's.

Hackeling said that Nancy Cooper told her that, initially, Brad Cooper repeatedly denied the affair and that the other woman was making up the story.

"I think, because he denied it, she wasn't sure if it really happened," Hackeling said. "I think, at first, she wanted to try to make it work."

Nancy Cooper said Brad Cooper admitted to the affair during a marriage counseling session in early 2008, Hackeling added.

"When she did find out, it kind of gave her peace, knowing she couldn't make the marriage work," she said.

Nancy Cooper's twin sister, Krista Lister, testified Monday that Brad Cooper had been so insistent that the affair did not happen that Nancy Cooper, at one point, had started trying to forgive herself for thinking it happened.

"Nan always thought she married the safe guy, the guy that wouldn't cheat on her, and (would be her) best friend and just wouldn't hurt her," Lister said. "She was devastated."

During cross-examination, defense attorneys questioned Lister about Nancy Cooper's relationships with other men. Lister testified that her sister admitted that she had met a man on a trip to Florida early in her marriage in 2001 but that Lister never knew of an alleged affair that Nancy Cooper had in 2005.

Jenipher Free and Shirley Hull, parents with children attending Triangle Academy Preschool, where the Coopers' oldest daughter attended, also took the witness stand Tuesday.

Each had similar accounts of hearing and seeing Nancy and Brad Cooper arguing outside the school in May 2008, and each said Brad Cooper used foul language at his wife in front of their children.

"I heard Nancy yelling (at Brad) to give her the kids and saw Brad blocking the car, not letting her get to the kids," Free testified.

Their accounts also differed some, but neither said they heard Brad Cooper threaten his wife or touch her.

The last witness to testify Tuesday was Chris Frye, a security investigator for Cisco Systems Inc., where Brad Cooper worked as an engineer specializing in Voice over Internet Protocol, a method of transmitting sound as data over the Internet.

Fry told jurors that Brad Cooper had set up a special phone number assigned to  Cisco's Paris office that forwarded any phone callsto that number to his office in Research Triangle Park. He also testified that Brad Cooper and he had an online chat about software for encrypting data on computers and also about software used for wiping, or deleting, information from drives.