By Ted Siefer
DOVER N.H. (Reuters) - Seth Mazzaglia was overtaken by "the darkness" when he strangled a 19-year-old University of New Hampshire student in 2012 for rejecting his sexual advances, a state prosecutor said on Wednesday.
The trial of Mazzaglia, 31, for the killing of UNH student Elizabeth Marriott has riveted the New England state for weeks with details of the occult, sadomasochism and romantic betrayal. It entered its final phase on Wednesday with closing arguments, and the jury will begin deliberations on Thursday.
"This is not just some regular guy trying to get sex," Assistant Attorney General Geoffrey Ward told jurors, referring to Mazzaglia. "This defendant made clear if his sexual desires were not fulfilled 'the darkness' would get the better of him."
Mazzaglia's ex-girlfriend Kathryn McDonough, 20, has testified she lured Marriott to the apartment the couple shared as a sex offering for Mazzaglia. She said Mazzaglia strangled Marriott with a rope and raped her lifeless body after she rejected his advances.
Mazzaglia has denied the charges and his lawyers have sought to the undermine McDonough's credibility, portraying her as a manipulator who changed her story in exchange for a shorter prison sentence. She was given a plea deal for her testimony.
Mazzaglia's defense has also argued that it was McDonough who was responsible for Marriott's death, by engaging in rough sex with her. Before her plea deal, McDonough first told attorneys that Marriott died from a seizure.
"She needs this more than anything. You don't think she's willing to lie?" defense attorney Joachim Barth told the jury in Strafford County Superior Court, referring to her plea deal.
Marriott’s body has never been recovered. McDonough testified she and Mazzaglia put Marriott's body into a suitcase and dropped it into a river near the Portsmouth harbor.
Over 19 days of testimony, details emerged of a twisted fantasy life shared by the couple that featured multiple personas, tarot cards and visions of taking over the world. Mazzaglia never took the stand.
Mazzaglia is charged with first-degree murder and could face life in prison if found guilty by the jury.
Under the plea agreement, McDonough is serving 18 months to three years in prison for charges that include witness tampering and hindering the investigation.
(Reporting by Ted Siefer; Editing by Richard Valdmanis, Doina Chiacu and Eric Beech)