Human remains found as DiNardo's parents face grand jury Thursday

One week after the first of four young men in Bucks County went missing, investigators have discovered human remains inside a 12-foot-deep grave on a Solebury Township property. Meanwhile, the owners of the property, who are the parents of a person of interest, will face a grand jury this morning.

In a midnight press conference, Bucks County District Attorney Matthew Weintraub announced that human remains belonging to missing 19-year-old Dean Finocchiaro were found inside that grave along with other remains. The district attorney says cadaver dogs led them to that location earlier in the week.

22-year-old Mark Sturgis, 21-year-old Thomas Meo, and 19-year-old Jimi Taro Patrick remain missing Thursday morning.

In a Thursday morning press conference, Weintraub only provided an updated tip line for the FBI, and a further biography on Jimi Taro Patrick. The FBI tip line is 1-800-CALL-FBI.

TIMELINE: Search for missing boys, investigation in Bucks County

Those remains were found on a farm owned by the parents of 20-year-old Cosmo DiNardo, who was named a person of interest in the case back on Tuesday.

Wednesday afternoon, authorities charged Cosmo with stealing and attempting to sell a car belonging to Meo. The car was found on a property belonging to the DiNardo family in Solebury Township and was found with Meo's diabetic kit inside. Bail was set a $5 million.

DiNardo also had been arrested Monday and held on $1 million bail on an old gun charge, before his father paid $100,000 to bail him out Tuesday. The charge stems from accusations that DiNardo was caught with a shotgun and ammunition in February despite a prior mental health commitment.

MORE: Man held on $5M cash bail amid search for 4 missing men

The back-to-back arrests bought investigators time as they scoured the farm and other spots across the county for clues to the men's disappearance, Weintraub said. He hoped the higher bail would hold him even longer, but acknowledged it might not.

DiNardo's parents, Antonio and Sandra DiNardo, own the farm in upper Bucks County, a bucolic area with rolling hillsides, new housing developments and historic sites. The DiNardos also own a concrete company and trucking company headquartered on Castor Avenue where heavy equipment, including backhoes can be found.

Antonio and Sandra DiNardo will face a grand jury Thursday morning.

That grand jury investigation that could provide some answers in the case, including details on Cosmo DiNardo's whereabouts during the last week.

An attorney representing the couple, Fortunato Perri Jr., issued a statement earlier Wednesday saying they sympathize with the families of the missing men and are cooperating "in every way possible with the investigation."

"I can tell you they are doing everything in their power to cooperate with law enforcement's investigation at this point," Perri added.

MORE: Parents of Cosmo DiNardo headed to grand jury Thursday morning

Sources tell FOX 29 that in addition to his parents, Cosmo DiNardo himself may be called before the grand jury Thursday. It's unclear if he will testify. He could possibly invoke the fifth amendment, refusing to incriminate himself.

The FBI had been using heavy equipment to dig a deep ditch on the farm property, and then sifting through each bucket of dirt by hand.

At least some of the missing men are friends, but it's unclear how well they knew DiNardo, if at all. FOX 29 has learned that Jimi Taro Patrick and DiNardo both attended Holy Ghost Preparatory School, and Mark Sturgis and Thomas Meo worked together.

In the February gun charge he still faces, DiNardo is accused of illegally being in possession of a shotgun and ammunition because of a previous involuntary commitment to a mental health institution. An affidavit in that case said he is "known to be suffering from mental illness."

His social media posts suggest an avid interest in hunting, fishing and Air Jordan sneakers, which he appeared to sell online. He had enrolled in a nearby college at one point as a commuter student, with hopes of studying abroad in Italy, according to an article on the college website. He had a few other brushes with the law since turning 18 over traffic violations and other minor infractions.

Authorities have been giving regular press conferences at 11 a.m. and 3 p.m. Thursday's 3 p.m. press conference was canceled, and it was unclear if another would be held later in the day.