A 21-year-old man who enlisted his cousin in the savage killings of four men on a farm in the Philadelphia suburbs last summer pleaded guilty Wednesday to murder charges that will put him in jail for life, as family members of the victims lashed out in the courtroom.

Cosmo DiNardo's plea came after he confessed to the killings of the four men and told authorities the location of the bodies of 19-year-old Dean Finocchiaro, Mark Sturgis, 22, Tom Meo, 21, and Jimi Tar Patrick, 19, last year in exchange for avoiding the death penalty.

DiNardo's cousin, 21-year-old Sean Kratz, rejected a plea deal. Prosecutors said they will seek the death penalty at Kratz's forthcoming trial.

At one point DiNardo said he was sorry to the "poor parents" of his four victims, which a judge said was insincere, according to FOX29.

"To you, human lives are disposable," Judge Jeffrey Finley told DiNardo. "They have no value."

Melissa Fratanduono, the mother of Tom Meo, cursed at DiNardo during the sentencing, saying it has "taken everything" for her not to kill him herself.

"You've lived your whole life protected. In prison, you'll meet savage. And I promise you, it won't look like you." — Mark Potash, father of victim Mark Stugis,

Another family member, the father of Mark Stugis, told the 21-year-old his only way out of prison is "wearing a toe tag."

"That's the least we all deserve," Mark Potash said.

Potash also called DiNardo a "perfect example of someone who started at the top and worked your way down to the gutter."

"You think you're savage?" Potash said. "You've lived your whole life protected. In prison, you'll meet savage. And I promise you, it won't look like you."

WRONGFUL DEATH LAWSUIT FILED IN GRUESOME MURDER CASE AT PENNSYLVANIA FARM

DiNardo came from a wealthy family, sold marijuana and boasted on social media that he was "a savage," frequently holding guns in photos.

Authorities said he was the mastermind of the killings on his family's 90-acre farm in Solebury Township, located about 30 miles north of Philadelphia and charged him in all four deaths. Kratz was charged in three.

Police found the men after a five-day search and said three were lit on fire and placed 12-feet deep in a metal tank that was converted into a cooker that he labeled a "pig roaster.” DiNardo allegedly lured them to his family's farm under the guise of making pot deals.

DiNardo quickly confessed, and District Attorney Matthew Weintraub said authorities might never have found 19-year-old Jimi Taro Patrick's body unless DiNardo told them where it was.

COSMO DINARDO, COUSIN, PLEAD NOT GUILTY IN GRUESOME PENNSYLVANIA MURDERS

DiNardo has a history of mental illness, including an involuntary commitment and a schizophrenia diagnosis, but his lawyer said mental health professionals weren't sure they could have presented an insanity defense.

"Mental illness is real, mental illness is sad, and sometimes it can be tragic," lawyer Fortunato Perri told the court.

The families of the slain men are also suing DiNardo's parents, Antonio and Sandra DiNardo, who own the Solebury farm property and construction and concrete companies in Bensalem, where they live. The families say DiNardo's parents shouldn't have allowed him access to a gun, which was barred by law due to his commitment.

In his confession, DiNardo acknowledged selling handguns to local residents. Five months before the killings, police charged him with having a shotgun.

The Associated Press contributed to this report.