Mazzaglia convicted of murdering N.H. student

Jury deliberates 8 hours in monthlong trial that described domination, lurid sex details

Seth Mazzaglia was convicted of killing 19-year-old Elizabeth “Lizzi” Marriott.
AP (left); Facebook photo
Seth Mazzaglia was convicted of killing 19-year-old Elizabeth “Lizzi” Marriott.

Robert Marriott bowed his head.

“Lizzi is gone,” he said, looking up at the cameras, his voice tight with grief. The hands of loved ones gripped his shoulders.

“We are very grateful that the jury returned a guilty verdict for first-degree murder because it will keep the convict in prison for the rest of his life.”


A 31-year-old Dover, N.H., man was convicted Friday of first-degree murder in the October 2012 slaying of 19-year-old Elizabeth “Lizzi” Marriott, a University of New Hampshire student from Westborough.

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Jurors in Dover deliberated for about eight hours before finding Seth Mazzaglia guilty of first-degree murder by strangulation and a second count of first-degree murder in connection with felonious sexual assault.

He was also convicted of conspiring to tamper with witnesses, and conspiring to falsify physical evidence, for his attempts to cover up the murder.

As the verdict was announced, Mazzaglia’s face remained impassive.

The monthlong trial was dominated by one voice: Mazzaglia’s former girlfriend, 20-year-old Kathryn McDonough, who testified for 10 days.


She told the jury about her relationship with the defendant, characterizing him as controlling and abusive, the master in their bondage-filled sexual relationship. She talked about their shared belief in dragons, tarot cards, past lives, and alternate personas. And she told the jury, in sometimes graphic detail, what happened Oct. 9, 2012, the night Marriott died.

She said she lured Marriott, a Target co-worker, to the couple’s Dover apartment as a sexual offering for Mazzaglia, who had demanded another woman in the bedroom.

But McDonough said when her co-worker twice rejected Mazzaglia’s advances, he got angry. He selected a rope the couple used in bondage sex, strangled Marriott, and raped her lifeless body, McDonough said.

The couple then put Marriott’s body in a suitcase and dumped it into the strong current off of Peirce Island, McDonough said. The body has not been found.

The defense sought to undermine McDonough’s credibility, relentlessly questioning her narrative. Defense lawyer Joachim Barth said it was McDonough who killed Marriott during bondage sex, and that she changed her story to blame Mazzaglia after accepting a plea deal in exchange for her testimony.


McDonough is serving a 1½-to-three-year sentence for conspiracy, hindering prosecution, and witness tampering.

Robert Marriott said the jury’s decision will protect young women who could have become “additional victims” of Mazzaglia’s. But, he said, that still is not enough.

“Unfortunately, a trial, even with a conviction, cannot console us over the loss of Lizzi. We will always miss her and wonder what could have been,” he said, on the verge of tears.

He said enduring the trial proved “torturous,” and that the defense mischaracterized his daughter, “a defenseless victim.”

“The truth of what happened to Lizzi is horrendous, and every time it has been told, it has reinforced the despair that we feel,” he said.

Assistant Attorney General Geoffrey Ward thanked the jurors and extended his sympathies to the Marriott family.

‘“We all wanted to bring her home, but were unable to do so,” he said. “The Marriott family has exhibited dignity, perseverance, determination, and patience.”

A spokeswoman at the Dover office of the New Hampshire Public Defender program, which provided Mazzaglia’s defense team, said the office was “unauthorized to give any type of statement.”

The jury, seven women and five men, said at noon Friday it had reached verdicts and announced them shortly after 1 p.m.

Juror Maria Clifford told the Associated Press that the panel believed McDonough, who the juror said “had nothing left to lose” on the stand.

To help forge a sense of fairness in her mind, the juror said she tried to regard Mazzaglia as if he were a family member.

The verdict brought a quick end to a trial that was shocking for many in tight-knit Dover, population 30,000. People said they could not believe something so lurid could happen in a city so quaint.

A court clerk will arrange a sentencing date in the near future, said Strafford County Superior Court Judge Steven Houran.

Ward, the prosecutor, said in closing arguments that Mazzaglia was a cold-blooded killer.

“This defendant made clear if his sexual desires were not fulfilled, ‘the darkness’ would get the better of him,” he said. “He was not in control of Lizzi, and he couldn’t stand it. And he killed her for it.”

Claire McNeill can be reached at or on Twitter at @clairemcneill.