WARNING: DISTURBING CONTENT

A man accused of strangling his former high school classmate to death and then throwing her body off a bridge in New Jersey was captured on video describing how he took 30 minutes to kill the girl. He is also seen describing how he had timed the whole thing on his phone.

Liam McAtasney was secretly recorded telling a friend, who was working with detectives at the time, about how he murdered 19-year-old Sarah Stern for the money she had received from her mother.

The video was filmed just days before McAtasney and an alleged accomplice Preston Taylor were charged with the murder in 2017.

The authorities said that the two teens, both then 19-years-old, threw Stern's body off a bridge before they left her car there to make it seem like she had taken her own life, the Daily Mail reported.

The jurors were then shown the disturbing video during McAtasney's murder trial on February 7.

McAtasney can be heard telling his friend, Anthony Curry, in the video: "I pretty much hung her. I picked her up and had her dangling off the ground. It took me a half hour to kill her. I set a timer."

McAtasney also says in the video that he shoved a shirt down the teen girl's throat and even placed his finger on her nose. He then says that the biggest problem had been Stern's dog but it just "laid there and watched as I killed her".

The killer then told Curry that he needed Taylor's help to dump Stern's body off the Route 35 bridge because he hadn't realized how heavy she was.

McAtasney then continued to talk about how he believed he was going to get $100,000 by stealing it from Stern's inheritance after he killed her, but that he managed to get only $8,000.

He said: "The worst part of it is I thought I was going to come out $50,000 to a $100,000 in my pocket. She had one safe that she took money out, and she only had $10,000. And this money, I don't know if it was burnt or something, it's f*****g old money. Terrible quality. I don't even know if I can put any of it in the f*****g bank."

McAtasney then told Curry that he was the only one beside himself and Taylor who knew about Stern's murder, and Taylor would kill him if he told the police about it.

He is alo heeard saying in the video: "I don't feel any different, I really don't think about it. You always think you're going to try all these new things and change, but it just doesn't do anything. It's weird."

Curry replied: "It's a f****** movie, man." McAtasney then said: "It's your life. You might as well make it one. What are you going to live some boring a** life?"

Curry finally came forward to the police in January 2017 after his father contacted a retired officer from the Bradley Beach department. He testified at McAtasney's murder trial last week that the killer had first told him of his vile plans to strangle Stern on Thanksgiving 2016.

Curry said he didn't think much of the bizarre conversation but then started getting worried when he learned that Stern was reported missing on December 3, 2016.

Stern, McAtasney, and Curry all attended the same high school together.

Both the victim and the killer were in Stern's house in Avon-by-the-Sea when she discovered a shoebox filled with cash that had belonged to her late mother.

Curry said in court: "He told me he was going to meet up with Sarah, she had found this money. They were going to count it together. He was going to choke her, choke her out. Bring her to the bridge, throw her off and Preston was going to drive the escape vehicle. And they were going to bury the money, and leave the keys in the ignition and make it look like she killed herself."

After Stern disappeared, Curry said that he and McAtasney had spoken to each other via Snapchat because of the ability to get rid of all messages. Curry took a video of the messages and these led the Monmouth County Prosecutors to be able to get a warrant for consensual recording.

McAtasney's attorney, Carlos Diaz-Cobo, however, argued that the video was not a confession and that his client made up the elaborate story just to impress his friend. He said: "The statement to Anthony Curry is not a confession. It's an elaborate lie, it's an audition. It's a script. It's not true. ... A young, immature boy decided he was going to use this unfortunate disappearance and make up this story."

Curry then admitted during his cross-examination that McAtasney had a habit of sharing fantastical stories with him and that the pair often spoke about various films together. The defense claimed that there was also no physical evidence to support any of the accusations.

Stern's body is yet to be found.