DOVER, N.H. (AP) -- A jury on Friday convicted a 31-year-old man of killing and raping a University of New Hampshire college student following a trial filled with lurid details of sexual domination, experimentation and violence.
The jury in Strafford Superior Court found Seth Mazzaglia guilty of first-degree murder in the death of 19-year-old Elizabeth "Lizzi" Marriott of Westborough, Massachusetts, in October 2012.
The key witness, 20-year-old Kathryn McDonough, was Mazzaglia's girlfriend when she lured Marriott to their apartment. She testified that Mazzaglia wanted another woman to join their sexual escapades, which included bondage and discipline.
McDonough first told investigators that Marriott died during rough sex between the two women that involved restraints. After getting immunity from prosecution, McDonough changed her story and said Mazzaglia strangled Marriott then raped her.
Mazzaglia was found guilty of one count of first-degree murder that stated he strangled Marriott "before, after or while" sexually assaulting her. He also was convicted of conspiracy to falsify evidence and conspiracy to tamper with witnesses.
He will be sentenced to life in prison without the chance of parole.
Jurors began deliberating Wednesday, after hearing 19 days of testimony. McDonough was on the stand for 10 of those days.
The trial hinged McDonough's credibility. Mazzaglia did not testify.
McDonough initially told investigators that she killed Marriott during consensual sex but later said she made that story because she loved Mazzaglia, thought they still had a future together and wanted to protect him.
Defense lawyers, though, painted her as an opportunistic liar who killed Marriott then changed her story when she found out she could cut a deal and get less time in prison if she pinned the crime on her ex-boyfriend.
The deal was conditioned on her testifying truthfully.
In court, she testified that Mazzaglia was the sexually dominant partner in their relationship and became angry when she left for nearly two weeks at theater camp without recruiting a sex partner for him. As what she called punishment, Mazzaglia told her to lure a woman -- Marriott -- to the apartment on Oct. 9, 2012.
After a game of strip poker which prosecutors say Marriott willingly joined, Mazzaglia suggested she kiss McDonough. Marriott said no, saying she was in a committed relationship. Mazzaglia then asked if she would watch as he and McDonough had sex. She again said no.
Prosecutors said the domineering Mazzaglia was unaccustomed to being rejected so, as the two women watched a movie, he sneaked up behind Marriott and choked her with a rope. McDonough testified that she left the room briefly and when she returned, found Mazzaglia raping Marriott's limp body.
The two of them threw her in a river that feeds into the Atlantic Ocean. Marriott's body has never been found.
Mazzaglia's lawyers said McDonough, who pleaded guilty to hindering prosecution and is spending 1 1/2 to 3 years in prison, was interested in experimenting with women and initiated the sexual activity that night in the apartment she shared with Mazzaglia.