Raleigh, N.C. — Search warrants returned Tuesday paint a negative picture of the relationship between a slain Wake County mother and her husband, who is a suspect in the case.

Jason Young and his wife, Michelle Young, had a "volatile" relationship that included violent arguments and infidelity on his part, according to affidavits that Wake County sheriff's investigators filed to support their request to get access to e-mail accounts registered to Jason Young.

Michelle Young, who was five months' pregnant at the time, was found beaten to death in her Wake County home on Nov. 3, 2006.

In the new warrants, dated March 10, investigator R.C. Spivey says witnesses told detectives that the Youngs "notoriously didn't get along" and that they had witnessed loud fights between the couple that would sometimes last for hours.

A friend described how on one occasion, Jason Young "punched holes in the walls" and "ripped the door off" its hinges, Spivey wrote.

Another friend told investigators Jason Young told them he was "sick of" his wife, that she was "driving him crazy."

Investigators were also informed by another friend that "it was pretty well known that Jason was not real faithful" to his wife and that Michelle Young might have been planning to divorce him.

Michelle Young also found women's underwear that did not belong to her in the couple's bed, another friend told investigators.

"Jason made up some story about the maid. She was not sure exactly what," the warrant states.

The warrants also contains a July 12, 2006, e-mail Jason Young sent to his wife on a day when he was home with their daughter, Cassidy. It describes him as being frustrated because he was not able to get any yard work done because the power was out and Cassidy was unable to watch TV.

"I am taking beer and her to pool. I am in a mood that makes our trip to myrtle [sic] seem mild, pray the beer kicks in," the e-mail states. "I could kill u [sic] for not letting me finish the yard work this morning."

The latest warrants are among nearly two dozen in the case that indicated Jason Young has been a focus of the criminal investigation.

No criminal charges have been issued, and authorities generally have declined to comment on the case.

Jason Young told investigators he was out of town on business when his wife was killed, but he has otherwise been uncooperative with investigators. He spoke to them once and, under a court order, gave DNA samples.

He has since moved with his daughter to Western North Carolina, where his family lives.

In January, a judge ruled in a wrongful death lawsuit filed by Michelle Young's mother, Linda Fisher, that Jason Young was responsible for Michelle Young's death. Young missed a deadline to respond to that lawsuit, so the judge ruled for Fisher by default.

Legal experts say the ruling has nothing to do with guilt or innocence, but it means Young won't be able to collect benefits from his wife's life insurance policy.

Last month, Young and Linda Fisher reached a settlement in a custody dispute over Cassidy. He and Michelle Young's sister, Meredith Fisher, will share custody.