The family of one of the four men allegedly killed by Cosmo DiNardo on his family's Bucks County farm in July has filed a wrongful death suit that in part blames DiNardo's parents for allowing their mentally ill son to have access to guns.

The claim is one of several made in the suit, filed Tuesday in Philadelphia by the parents of Mark Sturgis against DiNardo, a 20-year-old Bensalem resident; his cousin Sean Kratz; and DiNardo's parents, Sandra and Antonio.

Sturgis, 22, of Pennsburg, was one of the four men found buried on the DiNardo family farm in Solebury Township after an exhaustive search that drew national attention. Also killed were Jimi Patrick, 19, of Newtown; Dean Finocchiaro, 18, of Middletown; and Thomas Meo, 21, of Plumstead.

DiNardo is charged with killing each at the farm after bringing them there for drug deals. Kratz, 20, of Philadelphia, is charged as a conspirator in three of the killings.

Both pleaded not guilty to murder and other offenses at their Dec. 14 arraignments in Bucks County Court. Prosecutors have made a deal with DiNardo to spare him the death penalty if he pleads guilty at a later date, and have said they are still deciding whether to pursue the death penalty against Kratz.

The lawsuit is the first civil case filed in the murders.

In addition to blaming DiNardo and Kratz for Sturgis' death, it contends that the elder DiNardos knew their son "suffered from mental health issues, violent tendencies, and a proclivity for utilizing firearms" yet didn't prevent him from getting access to a Smith & Wesson .357 handgun — registered to Sandra DiNardo — allegedly used to kill Sturgis. The parents, the lawsuit says, created a "dangerous condition" on their expansive farm by allowing DiNardo to have access to the property and farm equipment allegedly used in the slayings or to hide the bodies.

"With this lawsuit, the heartbroken parents of Mark Sturgis intend to hold accountable everyone responsible for the horrific death of their son, not just those who pulled the trigger," attorney Robert Ross said in a statement Wednesday. "This includes those who negligently and carelessly permitted either of the accused to gain access to firearms and equipment used in these heinous crimes."

Ross said Sturgis' father described his son as a "wonderful young man" who loved sports and working construction with his dad.

An attorney for Antonio and Sandra DiNardo said the couple had done "everything humanly possible" to help their son and had been making progress before the killings.

"There were not four families victimized by this matter, there were five families. The DiNardo family has been absolutely crushed and devastated by what's occurred," said lawyer George Bochetto. "It's regrettable that they would be subject to lawsuits when they themselves are grieving so heavily over all of this."

Kratz's criminal attorney, Craig Penglase, said the filing "added unnecessary complication" to the criminal case.

"While any aggrieved party has the absolute right to file a civil lawsuit in this matter, it's important to remember that there was absolutely no reason to file this suit before the conclusion of the criminal proceedings," Penglase said.

Fortunato Perri Jr., one of Cosmo DiNardo's criminal attorneys, could not immediately be reached for comment Wednesday morning.