Dangerous Games

In 2012, Lizzi Marriott was a 19-year-old New Hampshire student when she disappeared after visiting her co-worker, Kat McDonough, and Kat's boyfriend, Seth Mazzaglia, in their apartment. Kat initially claimed Lizzi's death was accidental, but later testified that Seth strangled Lizzi with a rope after she rejected his sexual advances. "48 Hours" correspondent Troy Roberts reports. This classic "48 Hours" episode last aired on 9/19/2015. Watch all-new episodes of “48 Hours” on Saturdays and stream on demand on Paramount+.