The quadruple murder trial against an ex-cop, who shared a cell with Jeffrey Epstein, begins this week after four bodies were found buried in the backyard of his New York home in 2016.

Nicholas Tartaglione, 55, was allegedly selling cocaine, steroids and other drugs after his 2008 retirement from law enforcement when he accused one of his associates, Martin Luna, of stealing more than $200,000 from him, federal prosecutors allege. 

On April 11, 2016, Tartaglione allegedly lured Luna to a bar in Orange County, New York, where Luna was accompanied by his nephew, Miguel Luna; his niece's fiancé, Urbano Santiago; and a family friend, Hector Gutierrez. 

All four men went missing after that, according to prosecutors, who said after Tartaglione's arrest in December 2016 that they were "in the wrong place at the wrong time."

RETIRED NY POLICE OFFICER CHARGED WITH KILLING FOUR MEN IN DRUG DEAL

This undated photo shows former New York police officer Nick Tartaglione. Trial begins this week in his quadruple murder case. (Nick Tartaglione)

Then-federal prosecutor Preet Bharara called the alleged murders a "gangland-style" execution. 

Miguel Luna, Santiago and Gutierrez weren't part of the alleged drug-running operation, according to family and prosecutors. 

Tartaglione allegedly zip-tied Martin Luna and dragged him to the property , about 20 miles from the bar, where he was allegedly murdered. 

Alleged co-conspirators helped Tartaglione force the three other men to the property, where they were fatally shot and buried with Martin Luna, according to court papers and previous statements by federal prosecutors. 

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Tartaglione faces life in prison, if convicted, although prosecutors initially intended on seeking the death penalty against him. 

Last year, Attorney General Merrick Garland reversed that decision. 

Tartaglione's case went from an alleged, grisly drug-related quadruple homicide in lower New York state to national news when he became cellmates with Epstein at the Metropolitan Correctional Center in Manhattan.

FILE - This March 28, 2017, file photo, provided by the New York State Sex Offender Registry, shows Jeffrey Epstein. A fund set up to provide money to victims of financier Epstein has abruptly suspended payouts. The Epstein Victims’ Compensation Program said Thursday, Feb. 4, 2021, it has temporarily run out of funds. (New York State Sex Offender Registry via AP, File)

On July 23, 2019, Epstein was found in his prison cell semi-conscious and balled up in the fetal position with marks on his neck, and there were accusations that Tartaglione "roughed him up."

He was questioned, but the former cop and his lawyer fought the accusations and charges were never filed.

A dark cloud of suspicion still lingers over the incident because video surveillance footage was "mistakenly" deleted by prison staff, and Tartaglione was inexplicably found with a cellphone. 

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The Metropolitan Correctional Center, which is operated by the Federal Bureau of Prisons, stands in lower Manhattan on November 19, 2019 in New York City. Two Bureau of Prisons guards have been charged by a federal grand jury with conspiracy and filing false records in connection with their work on the night Jeffrey Epstein died while in custody at the facility. (Photo by Spencer Platt/Getty Images)

Epstein died of an apparent suicide the next month – on Aug. 10, 2019 – but Tartaglione wasn't in the cell at that time. 

After Epstein's death, the former police officer requested a transfer to a different prison, claiming he was being harassed by prison guards, according to court documents. 

Billionaire Jeffrey Epstein in Cambridge, MA on Sept. 8, 2004. (Photo by Rick Friedman/Rick Friedman Photography/Corbis via Getty Images)

There were other allegations that Tartaglione was assaulted by correction officers, according to court papers. 

"The clear message Mr. Tartaglione has received is that if he conveys information about the facility or about the recent suicide, there will be a price to pay," his attorney, Bruce Barket, wrote in a letter to the judge.

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"The continuing and seemingly unresolvable problems with the conditions of Mr. Tartaglione's confinement coupled with the unfortunate attempted suicide by a cellmate, to which Mr. Tartaglione is a critical witness, and the successful suicide of that same person makes his continued detention at the MCC inappropriate."

The Metropolitan Correctional Center in New York, where Jeffrey Epstein and Nicholas Tartaglione shared a cell. (AP)

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Jury selection in the quadruple murder case began in New York federal court in Westchester County, just outside of New York City, this week. 

Tartaglione has pleaded not guilty to all charges.