FILE - In this Aug. 14, 2014, file photo, Seth Mazzaglia looks back at his mother as he is escorted out of the Strafford County Superior Court in Dover, N.H. Mazzaglia was sentenced to life without parole for killing University of New Hampshire student Elizabeth Marriott. On Wednesday Nov. 16, 2016, Mazzaglia's appeal was heard before the state's Supreme Court. (AP Photo/Jim Cole/FILE)

CONCORD, N.H. - The New Hampshire Supreme Court is deciding whether a man convicted of killing a University of New Hampshire student should get a new trial based on his unsuccessful attempt to tell jurors about her sexual past.

Elizabeth "Lizzi" Marriott, of Westborough, Massachusetts, was a 19-year-old sophomore when she was killed in 2012. Prosecutors say Seth Mazzaglia (muh-ZAYL'-ee-uh) strangled her and dumped her body in a river, but his defence team argued at trial that she died accidentally during a consensual sex act.

Arguing his appeal Wednesday, Mazzaglia's attorney said barring evidence of Marriott's past sexual interests during the trial meant jurors wouldn't accept that she could have consented to the act in question.

"The jurors in this trial got two very vivid impressions. One is a vivid impression of the sexual techniques involved in the defence theory of what happened — and the state described those as dangerous and brutal and involved being tied down. The second vivid impression the jurors were going to get in this trial was about Miss Marriott and her extraordinary and admirable personal qualities," said attorney Christopher Johnson.

"The concern here is the juxtaposition of those two vivid impressions would create cognitive dissonance — it would crowd out the possibility that Miss Marriott could possibly have any interest in (such) activity," he said.

Justice Carol Ann Conboy appeared skeptical.

"You would say if the jury could consider that she had interest in these activities, it makes it more likely that the defendant didn't murder her? That's the link I'm having difficulty with," she said.

The state argued that allowing the evidence would have violated the state's rape shield law.

"This court has said explicitly that consent on one occasion does not equate to consent in the future," said Assistant Attorney General Geoffrey Ward.

Mazzaglia's then-girlfriend, Kathryn McDonough, initially told investigators that Marriott died during rough sex. After getting immunity from prosecution, she changed her story, saying that she lured Marriott to her apartment as a sex offering to her domineering boyfriend and that Mazzaglia killed Marriott after she rejected him. McDonough pleaded guilty to lying about the murder and served a three-year prison sentence.

Mazzaglia was sentenced to life in prison.

In June, the state Supreme Court ruled that information about Marriott's sexual past that was sealed during the trial should be made public during the appeals process, but it later reversed itself after prosecutors and Marriott's family objected. More than a dozen legal, law enforcement and victims' rights organizations also filed objections with the court.

On Wednesday, the New Hampshire Coalition Against Domestic and Sexual Violence said Mazzaglia's appeal relies on a "deeply flawed understanding of sexual consent."

"This is victim blaming at its worst," said Amanda Grady Sexton, the group's public policy director. "Lizzi was lured into a situation where she was raped and murdered; nothing about her alleged past thoughts or expressions would have changed or contributed to this."

The court likely will issue its opinion in three to six months.

News from © The Associated Press, 2016