Transcript for Alleged confession tape played in court in teen's murder
We are back wh that secret recording at the center of a murder trial in New Jersey. A young man in court accused of killing his childhood friend for her inheritance. Amy is here with all the details on this. Good morning. Good morning. The chilling video played in court is, frankly, too graphic and disturning to play in full for you. Prosecutors say Liam mcatasney planned Sarah stern's death for six months even studying the patterns of how she backed out driveway so it would look similar according to a new video played in court on Thursday that prosecutors say is a confession. 19-year-old Sarah stern was a promising young artist who went missing from her New Jersey home in December 2016. Stern's childhood friend, Liam mcatasney, was charged in her murder after allegedly strangling her and allegedly enlisting stern's prom date to help throw her body off a nearby bridge. Mcatasney is now currently standing trial for her murder. In court Thursday prosecutors playing what they say is a confession tape where he reportedly admits to the killing. It took me a half an hour to kill her. Reporter: The motive according to prosecutors getting their hands on Sarah's lockbox they believe was stuffed with cash. The worst part of it I thought I was walking out with 50 grand, 100 grand in my pocket. She had one safe that she took money out and she only had 10 grand. Reporter: The video was secretly recorded by police in a sting operation using mcatasney's friend Anthony curry. Curry telling police that mcatasney had approached him about a week before the murder with a plan to kill and rob his friend. Mcatasney'sorneys say his client fabricated the story for a horror film that curry, a filmmaker, was working on. Do we know why we're talking to you? No idea. Reporter: In these body cam recorded hours after her disappearance, mcatasney was asked about her whereabouts. I just know she's been trying to get away, telling me she's moving to Canada. Reporter: Prosecutors say he intentionally misled investigators hoping to throw them off. It's all so disturbing mcatasney has denied everything. He is facing life in prison without the possibility of parole if convicted. Preston Taylor, stern's prom date, has already pleaded guilty and testified against mcatasney. The defense is expected to present their case next week, guys, but it really just leaves you with a sickened feeling I your stomach. So sad. So unnecessary. Our heart goes out to Sarah stern's family to have to relive this and hear those details.
This transcript has been automatically generated and may not be 100% accurate.