Updated

Prosecutors say a man charged with killing a University of New Hampshire student in October plotted with a girlfriend to tell investigators she was killed accidentally during a consensual sex act.

Court documents released Tuesday charge 30-year-old Seth Mazzaglia (mah-ZAY-lia) of Dover with killing 19-year-old Elizabeth "Lizzi" Marriott during an attempted sexual assault on Oct. 9.

A Strafford County grand jury indictment charges him with first- and second-degree murder. He's also charged with hindering prosecution.

Mazzaglia faces two alternate theory first-degree murder charges. One alleges he strangled Marriott. The other alleges he used physical force to strangle her before, during or after an attempt to sexually assault her.

Marriott's body has not been found.