A man accused of murdering a University of Arkansas student told others "I think I hurt her real bad" but said he blacked out and couldn't remember what happened, a police affidavit says.

Zachariah Scott Marcyniuk, 28, of Fayetteville, was arrested Sunday evening in western Oklahoma, almost 10 hours after the body of his former girlfriend, Katharine Wood, was found in a bathtub.

She had complained that he was stalking her, friends and relatives said.

Marcyniuk remained in custody Tuesday in Sayre, Okla., while Fayetteville police seek to extradite him on a first-degree murder charge.

Marcyniuk told his parents before his arrest that he thought he hurt Wood, and he told a friend he must have blacked out and didn't remember what he did, according to the affidavit filed Monday with the Fayetteville police arrest warrant.

Wood, 24, a senior English major from Greenbrier, was found dead Sunday morning by police investigating a caller's report that a woman in her apartment complex seemed to be arguing with someone, police and the university said. The apartment complex is a few blocks off campus.

The affidavit said Wood appeared to be the victim of a violent struggle.

Fayetteville police Sgt. Shannon Gabbard told The Morning News that no gun or poison was involved in Wood's death.

"It looks like blunt force trauma, but that's speculative until we get results back" from the medical examiner in about a week, Gabbard said.

Marcyniuk was arrested in Oklahoma by a trooper who stopped him for speeding on Interstate 40 and discovered Marcyniuk was wanted by Fayetteville police.

A week before her death, Wood met Marcyniuk and he agreed to leave her alone, her brother, Matthew Wood, told police.

On Sunday, Marcyniuk showed up at his parents' house, saying he'd hurt Katie Wood, the affidavit states. He said he found out she was seeing someone else and went to her apartment. Marcyniuk said he grabbed her but didn't remember anything after that, according to the affidavit.

Friends and family said Wood had told them Marcyniuk was harassing her and "acting creepy." She told friends he stalked her at a nightclub and tried to spy on her cell phone calls.

"After they broke up three or four weeks ago, she'd become increasingly afraid," said Michelle Mustion, a friend of Wood's. "She'd talked to her mom and I about getting a restraining order, but she had reason to believe everything was going to work out."

Court records show Marcyniuk was sentenced to two years' probation in July 2005 for aggravated assault on a former girlfriend.

Marcyniuk was an art major who dropped out of school last month, officials said.