What to Know Convicted murderers Cosmo DiNardo and Sean Kratz are serving life in prison for the 2017 killings.

They killed four young men, then buried them at the farm in Solebury Township, Pa.

Investigation Discovery, a cable channel, will air a two-hour special on the slayings.

The infamous murders of four young men on a farm outside New Hope, Pennsylvania, in the summer of 2017 will be the subject of a two-hour television documentary that airs Monday, June 22.

The special, called "The Lost Boys of Bucks County," begins at 9 p.m. on Investigation Discovery. It will then be available on the cable channel's on-demand platform, IDGO.

"ID exposes the harrowing investigation which confounded law enforcement and speaks to the devastated families who are left in the wake of a senseless tragedy," according to a press release from the cable channel.

Last year, Sean Kratz was found guilty in the shooting death of Dean Finocchiaro. Kratz's cousin, Cosmo DiNardo, previously pleaded guilty in the murders of Finocchiaro and three other young men, Mark Sturgis, Tom Meo and Jimi Taro Patrick.

The murders all occurred on DiNardo's family farm in Solebury, Bucks County. They occurred in three separate incidents in which DiNardo lured the four men to his parents' farm under the guise of selling them marijuana.

Before the grisly discoveries of the men's bodies, their mysterious disappearances haunted the Philadelphia region for days.

NBC10 obtained exclusive audio of Cosmo DiNardo, the man behind the Bucks County killing spree, confessing to his crimes and describing them in detail.

During a 90-minute interview with detectives, which was obtained exclusively by NBC10 in 2018, Kratz admitted to shooting Finocchiaro in July 2017.

Click here to hear and read the grisly confessions

Kratz has been on suicide watch since Friday, which is standard for capital cases in Pennsylvania. Both he and DiNardo were expected to testify during the trial but neither took the stand.

Prosecutors at Kratz's 2019 trial described the killings as “one of the most horrific days in Bucks County history.”

Kratz and DiNardo were on a “mission to kill, rob and bury bodies,” Bucks County Deputy District Attorney Mary Kate Kohler said during opening statements at Kratz's trial. “It was one of the most horrific days in Bucks County history.”

Timeline: Murder of Four Young Men in Bucks County, Pennsylvania