The four missing Pennsylvania men, from left to right: Dean Finocchiaro, Thomas Meo, Mark Sturgis and Jimi Patrick. Photos courtesy of the Bucks County DA's Office

The search for four young men who went missing last week, igniting a massive operation that involved the FBI and U.S. Marshals, has taken a turn for the worse as investigators have found the remains of at least one of the four men.

Bucks County District Attorney Matthew Weintraub announced at a midnight news conference that investigators have found and identified the body of Dean Finocchiaro, 19, in a deep grave on Solebury Township property belonging to the parents of Cosmo Dinardo, who is currently being held on bail as a person of interest in the case. Upwards of 50 people have been searching the property since Sunday, including municipal police from five Pennsylvania townships, along with county detectives, state police and the FBI.

Weintraub declined to say how Finocchiaro might have died, but noted there was no doubt it was a homicide. He said additional human remains are in the more than 12-feet deep grave, with recovery efforts resuming this morning. Cadaver dogs led investigators to the grave site.

Finocchiaro was one of four men reported missing last week between July 5 and July 7. Still unaccounted for are Thomas Meo, 21; Mark Sturgis, 22; and Jimi Patrick, 19. More information is expected tonight or tomorrow as police continue to identify the remains found in the grave.

"There are additional human remains inside that grave, so this painstaking process will go on. We're not done yet," Weintraub said. "This is a homicide — make no mistake about it. We just don't know how many homicides."

Yesterday, police identified Dinardo, 20, as a person of interest in the disappearance of the four young men. He was arrested and arraigned, accused of stealing and trying to sell a car belonging to Meo.

"We allege that Cosmo Dinardo attempted to sell Meo’s vehicle for $500 to a friend whose identity we know but are protecting in the court documents for potential safety," Weintraub told reporters.

According to the Bucks County DA’s Office, the vehicle was found at 4 a.m. Sunday by police on the same property in Solebury Township where they would eventually find Finocchiaro’s remains. The title was found inside the car, unsigned by Meo.

"There was no legal exchange of that vehicle," Weintraub said. "Meo is known to be a diabetic, and his diabetic kit, which he never went anywhere without, was found in that vehicle.” Family members told investigators Meo could not have survived without his diabetes kit.

Dinardo was arraigned via video on Wednesday before Magisterial District Judge Maggie Snow on one count each of theft by unlawful taking and receiving stolen property, both third-degree felonies. First District Attorney Gregg Shore argued for an atypically high bail given the circumstances—including Dinardo’s history of severe mental illness, that the charges involved one of the missing men, and that Dinardo’s family property was at the center of the investigation.

Snow granted Shore's request, noting "the gravity of what is going on right now."

Despite the focus on Dinardo, Weintraub said the investigation is still wide open.

“We are going to go where it leads us. We don’t pick a person and then try to build a case around that person. That’s not fair to anyone. As of this moment, he remains a person of interest. But if others arise and we can name them, we will,” he said.