Seth Mazzaglia Indicted in Lizzi Marriott Murder Cover-Up

A Dover man charged with murdering a University of New Hampshire student a year ago was indicted Tuesday for allegedly conspiring with his ex-girlfriend to cover up evidence and to frame two other people for the crime.

According to court documents, a Strafford County Grand Jury returned an indictment of conspiracy to commit hindering apprehension or prosecution against Seth Mazzaglia of Dover.

State prosecutors allege that Mazzaglia and his ex-girlfriend, Kathryn McDonough of Portsmouth, conspired to hide key evidence on the night of Oct. 9, 2012 when they allege Mazzaglia murdered Elizabeth Marriott, 21, in his apartment and dumped her body into the Piscataqua River on Peirce Island.

The indictment also alleges that they deleted text messages on their cell phones from Marriott that talked about how she planned to visit the couple at Mazzaglia's apartment and how McDonough used her cell phone to text a message to Marriott asking her why she didn't come over.

Court documents also state that Mazzaglia and McDonough had several discussions where they agreed to concoct a fake alibi about their whereabouts on the night of Marriott's murder and that they later provided that fake alibi to State Police investigators a few days later.

The indictment also details several instances where Mazzaglia wrote McDonough letters from his Strafford County Jail cell in December where he conspired to frame Robert Gerkin and Paul Hicock. Court documents also state that Mazzaglia wrote McDonough about how he wanted to flee prosecution by going to a country that does not have an extradition treaty with the United States.

McDonough is currently serving a 1 1/2 to 3-year State Prison sentence after she was sentenced for her role in Marriott's murder in July.

Mazzaglia remains incarcerated at the Strafford County Jail in Dover awaiting trial for Marriott's murder. He recently assented to state prosecutors' motion to provide them with handwriting samples that could show he authored several jail house letters to McDonough about the case.