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Death of Westborough woman, 19, was accidental, N.H. suspect claimed

Elizabeth ‘‘Lizzi’’ Marriott

Elizabeth ‘‘Lizzi’’ Marriott

DOVER, N.H. — A man charged with killing a University of New Hampshire student in ­October initially told investigators that someone else strangled her, then later said he accidentally killed her during a consensual sex act, according to documents unsealed Monday.

Seth Mazzaglia is charged with killing Elizabeth ‘‘Lizzi’’ Marriott, 19, of Westborough, Mass., during an attempted sexual assault on Oct. 9. Prosecutors say it was not consensual.

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Mazzaglia, 30, described several scenarios when questioned about the death, including that he had gone home and found her dead, with his girlfriend and another couple in his apartment, according to a police affidavit. He later said he used a rope to strangle Marriott while they had sex, the affidavit said. The police affidavit also includes Mazzaglia’s account of dumping Marriott’s body in the Piscataqua River, Foster’s Daily Democrat reported. Marriott’s body has not been recovered.

Indictments allege an extensive coverup by Mazzaglia, of Dover, and by Kathryn ­McDonough of Portsmouth, then his girlfriend.

Mazzaglia also faces a murder charge alleging that he showed ‘‘extreme indifference to human life.’’ A public defender representing Mazzaglia has declined to comment on the indictments.

Last week, Mazzaglia waived his arraignment on murder charges. He had been scheduled to appear in court Thursday after being indicted by a Strafford County grand jury.

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