Grandparents Take Custody of Slain North Carolina Mom's Kids, Allege Dad Had Affair

The family of a slain North Carolina woman were given custody of her children late Wednesday after alleging in court documents that her husband had been having an affair.

Nancy Cooper's parents, Garry and Donna Rentz, claimed Brad Cooper was having an affair when she was murdered and had belittled her in front of their two young daughters, according to the family's custody complaint filed Wednesday and cited by the Raleigh News & Observer.

The complaint, characterized by investigators as a private matter, also alleges Brad Cooper withheld money from his wife, took the girls' passports to bar her from traveling to Canada, is emotionally unstable, threatened suicide in the last year and "poses a danger to the physical safety of the minor children."

Click here to read the petition.

Cary, N.C., Police Chief Patricia Bazemore announced Thursday that Nancy and Brad Cooper's two daughters, Bella, 4, and Katie, 1 1/2, had been handed over to Nancy's parents and her twin sister, Khrista Lister, late the previous night.

"I want to stress that this custody issue is a private civil matter between Nancy’s family and Brad. It was not initiated by the Town of Cary Police Department, and it was not a part of our investigation into Nancy’s murder," Bazemore said. "That said, any information that comes from this civil matter will be considered by investigators as we move forward in this case."

The custody transfer was an emergency petition filed by Nancy's parents and sister and granted by a judge on Wednesday.

At a press conference Thursday the family refused to elaborate on Brad and Nancy Cooper's relationship.

"We're not going to comment on that," Lister said.

But in court papers, Nancy Cooper's family said she'd recently hired a lawyer to deal with potential separation from her husband and custody issues.

When asked how the children are doing, Lister said, "They're doing really well."

Click here for photos.

Click here for a video.

The custody change comes as Brad Cooper's attorney issued a statement late Wednesday saying the 34-year-old father will continue to assist authorities in "bringing the killer or killers to justice" in his wife's murder investigation.

"Brad is devastated by the news of Nancy's death," the statement read. "To avoid jeopardizing the investigation, he will not be answering any questions from the press."

Bazemore said Thursday that investigators are continuing their search, a day after warrants were served on the Coopers' house and two vehicles. Six bags of evidence were taken from the Lochmere subdivision home on Wednesday afternoon, and a judge ordered Brad Cooper to submit blood and saliva samples for DNA testing.

"Investigations are as much about ruling things out as about ruling things in," Bazemore said. "We have still not named a suspect or a person of interest. Everyone in this case continues to be cooperative with us."

She would not take questions from the media on the investigation's progress. Instead, she turned the press conference over to Nancy's family, who spoke about their memories of the young mother.

Click here for Jonathan Serrie's on-the-scene blog.

"This is the single most important, heart-rending tragedy that has ever befallen our family," Donna Rentz said.

They remembered Nancy as a loving mother, a great friend and avid runner who had completed distance races.

The Rentzes traveled from Canada over the weekend to assist in the search for their daughter, as did her twin, her brother Jeff Rentz and her brother-in-law Jim Lister. Cooper and her husband are originally from Canada.

Authorities launched a murder investigation Tuesday after the 34-year-old's body was found in a Wake County, N.C., cul-de-sac, near where her husband said she'd gone jogging.

The mother of two small girls went for a routine run at 7 a.m. Saturday morning but did not come home by 9 a.m. to meet friends, as had been the plan, her husband said.

Nancy Cooper's parents do not believe she went running, according to court papers. They said Brad Cooper was the last person to see her alive.

Medical examiners confirmed the identity of the body found the previous evening by a man walking his dog miles from Cooper’s home, Bazemore said.

The couple reportedly was having marital problems, but friends told FOX News they did not think Brad Cooper had anything to do with her death.

A friend of Nancy Cooper reported her missing at 2:15 p.m. Saturday when she did not show up for a get-together. Police on Monday said they did not know why her husband wasn't the one to alert authorities that his wife had disappeared.

Bazemore declined to comment on whether or not Cooper’s body had suffered defensive wounds and would not confirm or deny reports that Brad Cooper had purchased bleach at a local convenience store just hours before his wife’s body was found.

The family asked residents of Cary on Thursday to tie white ribbons around their mailboxes and trees to remember the slain mother.

Click here to read more on this story from FOX affiliate WRAL-TV in Raleigh.

Click here to read more on this story from the NewsObserver.com.

FOXNews.com's Sara Bonisteel and The Associated Press contributed to this report.