FREEHOLD, N.J. -- A former classmate of a missing New Jersey woman admitted Monday he helped throw her body into a river and agreed to testify against another friend who’s accused of strangling the woman and stealing thousands of dollars from her.

Preston Taylor, 19, of Neptune City, pleaded guilty Monday to charges, including robbery, conspiracy, disturbing or desecrating human remains and hindering apprehension. In return, Monmouth County prosecutors agreed to drop a felony murder charge he also faced in the death of Sarah Stern, who was last seen alive Dec. 2.

Taylor agreed to testify against Liam McAtasney, who is accused of killing Stern and recruiting Taylor to dump her body. The men were longtime friends of Stern’s and Taylor was her junior prom date.

Prosecutors have said McAtasney killed Stern, 19, in her Neptune City home and robbed her, then called Taylor and asked him to hide her body. McAtasney’s attorney, Charles Moriarty, has maintained his client is innocent. McAtasney remains jailed pending trial.

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Taylor said Monday that they put Stern’s body in her car, then drove it and another vehicle to a bridge where they threw her body into the river. Taylor said they left Stern’s car at the bridge to make her death look like a suicide. Taylor also admitted knowing about McAtasney’s plan to rob and kill Stern, and said he received a share of the robbery’s proceeds.

McAtasney and Taylor were among nearly 100 people who volunteered to help search for Stern near the river shortly after her car was found. Prosecutors have said the duo participated in the search to deflect suspicion.

Stern’s remains have not been found.

Prosecutors said if Taylor does not fully cooperate, they would seek a first-degree murder charge against him. Taylor faces up to 20 years in prison when he’s sentenced July 21. His attorney, John Perrone, said he will instead seek a 10-year sentence.

“He’s got closure. He made admissions,” Perrone told reporters after the hearing. “This was something he had to get off his chest. He had to atone for this.”

Perrone also compared McAtasney to cult leader and convicted murderer Charles Manson, saying he exerted control over Taylor.

Liam McAtasney (left) is accused of killing Sarah Stern; Preston Taylor (right) is accused of desecration of a body for allegedly helping to dump Stern’s body Monmouth County Prosecutor’s Office

Shortly after Taylor entered his plea, prosecutors announced that a county grand jury had indicted McAtasney on charges of murder, felony murder, conspiracy, desecrating human remains, tampering with evidence and hindering apprehension or prosecution. They said he could face a life sentence with no chance for parole if convicted.

The indictment alleges that McAtasney killed Stern on Dec. 2 during a robbery that netted $10,000. McAtasney had plotted the killing for six months after learning that she had come into money from her grandmother, prosecutors said.

“We’re a long way away from trial and at this point, as far as my client’s concerned, all Preston had done is indicate that he (Taylor) was somehow responsible for what happened to the young girl,” Moriarty told the Asbury Park Press. “All I can tell you is my client had nothing to do with it.”