DOVER – The man behind the 2012 murder of a 19-year-old University of New Hampshire sophomore is a cold-blooded killer who was overtaken by “the darkness,” a state prosecutor said Wednesday in closing arguments.
“He was not in control of Lizzi, and he couldn’t stand it. And he killed her for it,” said Assistant Attorney General Geoffrey Ward, describing how 31-year-old Seth Mazzaglia allegedly strangled Elizabeth “Lizzi” Marriott of Westborough, MA, and raped her lifeless body.
Mazzaglia’s attorney, Joachim Barth, attacked the credibility of the prosecution’s star witness, the defendant’s former girlfriend. He said Kathryn McDonough, who spent 10 days on the stand, was a sociopath, a liar, and a manipulator who changed her story in exchange for a shorter sentence.
“If she is willing to manipulate Seth … you don’t think she’d want to lie to you? To manipulate you?” he asked the jury. “She needs this more than anything, and you don’t think she’s willing to lie?”
McDonough, who was given a plea deal for her testimony, told the court that, under pressure from Mazzaglia, she lured Marriott to the couple’s apartment as a sexual offering to him, and that she watched him strangle and rape Marriott. The defense has argued that McDonough herself killed Marriott during rough sex.
The trial, which included 19 days of testimony, featured strange and lurid testimony about the young couple, delving into everything from their sex life to their belief in alternate personas, dragons, and tarot cards.
Ward portrayed Mazzaglia as a controlling alpha male, the dominant figure in the relationship, who “used [McDonough’s] insecurities, her vulnerabilities and her teenage angst to draw her in.”
He said Mazzaglia was not “some regular guy trying to get sex.”
“This defendant made clear if his sexual desires were not fulfilled ‘the darkness’ would get the better of him,” Ward said.
Barth relentlessly attacked McDonough’s credibility, trying to raise reasonable doubt about the allegations.
The jury is to begin deliberating after receiving instructions on Thursday.
Mazzaglia allegedly murdered Marriott on Oct. 9, 2012, at the Dover apartment he shared with McDonough. Marriott’s body has never been found. McDonough testified that she helped Mazzaglia dump Marriott’s body in a suitcase off Peirce Island.