The lawyer for the widower of a slain North Carolina mother said Friday that his client did not kill his wife.

Seth Blum, one of two lawyers assisting Brad Cooper as investigators try to find the killer of his wife, Nancy, said wild speculation about his client's role in the case forced him to speak on his client's behalf.

"He is not a suspect, he is not a person of interest and he has been very, very clear with the police: He did not kill his wife," Blum said Friday afternoon, several hours before a candlelight vigil was to be held for Nancy in Cary, N.C.

Blum, who spoke a day after relatives of Nancy Cooper accused her husband of an affair in court papers, told reporters that 34-year-old Brad Cooper wished to mourn in private.

"The bizarre and unsupported theories that are floating around the television and the Internet have made it impossible for us to sit quietly and to say nothing," Blum said.

Earlier this week an emergency custody petition for the couple's children filed by Nancy Cooper's parents, Garry and Donna Rentz, and her twin sister, Khrista Lister, alleged that Brad Cooper was having an affair, had threatened suicide and posed a threat "to the physical safety of the children."

Click here to read the petition.

A judge granted the trio temporary custody of Isabella ("Bella"), 4, and Gabriella ("Katie"), who will turn 2 later this month. A custody hearing is scheduled for July 25, according to a report in the Raleigh News & Observer.

Blum would not answer questions related to the petition, saying he didn't wish to do anything to jeopardize the hunt for Nancy's killer.

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"Mr. Cooper has cooperated with the Cary police in every way that they have asked," Blum said. "He has answered their questions at numerous extensive interviews. He’s made himself, his cars and his home available for their investigations.

"He has asked and he continues to ask that anybody who has any information about the attack on Nancy to please come forward, please do it now, please share your information with the police immediately."

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Blum's statements echoed those of Nancy's father at a press conference Friday morning.

"This is an act of extreme cowardice by whoever did this, and I think if they have a shred of decency in their body, they would come forward and admit their guilt," Garry Rentz said.

The family said a candlelight memorial will be held Friday evening, and a memorial service was planned Saturday afternoon in Cary. Another service will take place next Wednesday in Edmonton, Alberta, where the family originally is from.

The family moved to North Carolina when Brad, who works for Cisco Systems, accepted a transfer from Calgary. The company secured Brad Cooper a temporary work visa; Nancy Cooper's was attached to his.

"Brad Cooper is a very private man," Blum said. "He’s not accustomed to the hot glare of the media spotlight. He never dreamed that he would see his face splashed across television news shows or his name in headlines, especially not under these terrible circumstances."

At a press conference Friday, officials refused to answer questions about the status of the investigation on the advice of the Wake County District Attorney's Office.

"Everyone continues to be cooperative with us, and I am pleased with the progress that we are making at this time,” Cary Police Chief Patricia Bazemore said.

Bazemore said she is confident that the case will be brought to an "appropriate conclusion." There will be no more news conferences until detectives make an arrest in Nancy Cooper's murder, she said.

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

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

The mother of two small girls went for a routine run at about 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.

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 said they didn't know why her husband wasn't the one to alert authorities that his wife had disappeared.

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 contributed to this report.