Inside the Case of N.J. Teen Allegedly Choked by Friend for 30 Minutes Before Being Thrown From Bridge

Last week, at his trial, prosecutors played a secret videotape that seems to show Stern's accused killer vividly detailing the crime

Photo: Source: Sarah Stern/Facebook

The details of her death are horrifying.

Authorities allege 19-year-old aspiring artist Sarah Stern was strangled in late 2016 over 30 minutes by a longtime friend who wanted to steal the inheritance money she’d received after her mother’s death. Using her car, her killer then drove her body from her Neptune City, New Jersey, home to a nearby bridge and threw it into the river below. Her body has not been found.

Last week, at his trial, prosecutors played a secret videotape that seems to show Stern’s accused killer vividly detailing the heinous crime — calmly recalling every moment of the killing he said he planned over six months.

The murder trial of Liam McAtasney, 21, continues this week. As the court proceedings unfold, here are five things to know about this disturbing case.

1. The Victim Grew Up with Her Accused Killer and Friend Who Helped Dump Body

Stern met McAtasney and Preston Taylor — who pleaded guilty to multiple charges and admitted to disposing her body — when the three were in middle school. By all accounts, they became fast friends, often acting out skits together at Neptune High School.

According to classmates, Stern referred to the other two as her “besties.” They were inseparable. “They knew each other’s locker combinations,” friend Morgan Randall previously told PEOPLE. “They were super close.”

The three were even part of a group that went to the junior prom together in 2015. Taylor, now 21, was Stern’s date.

Taylor admitted to prosecutors he assisted McAtasney, driving him back to their apartment after allegedly helping him throw Stern off the bridge. He has testified against McAtasney.

2. McAtasney and Taylor Helped Search for Stern After She Was Reported Missing

A week after Stern vanished, her father organized a search party. Dozens of people showed up to help — including McAtasney and Taylor.

“They said they were looking for answers,” said Randall, their classmate, who notes that the two posted flyers on social media and searched bushes near the bridge where Stern’s car was found.

According to friends, no one was surprised that they aided in the search. “I mean, they were best friends,” Randall told PEOPLE. “It would be surprising if they hadn’t tried to find her.”

3. McAtasney Complained About Amount of Cash Stern Had

Last week, jurors were presented with chilling, secretly-recorded video footage that prosecutors allege shows McAtasney confessing to the murder. Speaking candidly to a friend, he’s heard saying he planned the killing over a six-month period, monitoring Stern’s comings and goings so that he could later imitate those movements for nearby security cameras he’d spotted.

Prosecutors say McAtasney had his eyes set on Stern’s lockbox because it believed it was filled with tens of thousands of dollars in cash.

But early on in the recording, McAtasney grumbled about only walking away with $10,000, saying he was disappointed because he’d been told by Stern the amount of her inheritance was closer to $100,000.

Sarah Stern/Facebook; Monmouth County Prosecutor's Office/AP

“She only had 10Gs, and this money, I don’t know if it’s burnt or something, it’s old money, terrible quality,” he tells his friend, Anthony Curry, who approached police weeks after Stern’s slaying. “I don’t even think I can put it in the bank.”

He continued: “I did something really dumb and planned it out for a half a year.”

4. McAtasney Allegedly Timed Himself Strangling Stern

McAtasney, in the video, says he used a stopwatch app on his phone to gauge how long it took for her to die.

“Her dog laid there and watched while I killed her, and didn’t do anything,” he said. “I choked her out, dragged her to the back, put her in the bathroom, and then I had to go to work.”

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He continued: “I picked her up and had her just dangling off the ground,” he told Curry. “It took me a half-hour to kill her. I choked her out, and she was just laying there, having a seizure.”

He said he stuffed a towel down her throat to prevent her from vomiting, and then pinched her nose for 30 minutes.

5. Stern’s Body Is Still Missing

Five agencies — including the U.S. Coast Guard, the Monmouth County Sheriff’s dive team and the New Jersey State Police — have searched the area’s waterways but have been unable to find Stern’s body.

McAtasney’s attorney tells PEOPLE Stern might still be alive, but prosecutors disagree.

“She was murdered,” Monmouth County Assistant Prosecutor Megan Doyle said in court, “and her body was dumped by her friends.”

In the video played last week for jurors, McAtasney theorizes Stern’s body likely floated to the ocean.