What we know about the mystery of four missing men in Pennsylvania

Police teams searching for four missing men have made a heartbreaking discovery. Here's what we know about their mysterious disappearance and the investigation that has consumed this suburban community and riveted the nation.

Continuing coverage here

What happened?

What we know:

The four men went missing over several days last week near Philadelphia. They were last seen within miles of each other.

The men are Jimi Tar Patrick, 19, of Newtown Township in Bucks County; Mark Sturgis, 22, of Pennsburg in Montgomery County; Dean Finocchiaro, 19, of Middletown Township in Bucks County, and Tom Meo, 21, of Plumstead Township in Bucks County. Patrick was last seen July 5. The others went missing on July 7.

What we don't know:

It is not known why the men vanished or whether the disappearances are connected.

Did the four men know each other?

What we know:

Sturgis and Meo were close friends, CNN affiliate KYW-TV reported.

What we don't know:

Whether the other men knew each other isn't known, though there are "indications that some or all of the men knew one another," the Bucks County District Attorney Matthew Weintraub's Office said.

"I know more than I'm sharing on the relationships, and I have to keep it that way, unfortunately, to maintain the integrity of the investigation," Weintraub said.

It's not known whether any of the men knew anyone connected with the property where authorities have focused their search.

Where are the four men?

What we know:

Dean Finocchiaro, Jimi Patrick, Mark Stugis and Tom Meo pictured.

Finocchiaro's body was found Wednesday in what authorities described as a 12.5-foot-deep "common grave" on a 90-acre property in Solebury Township in Bucks County. "This is a homicide, make no mistake about it," Weintraub said.

Local and state police and the FBI had embarked on an "all hands on deck" foot-and-air search of the farmland, which is owned Antonio and Sandra Dinardo. Cadaver dogs led authorities to the common grave.

Meo's 1996 Nissan Maxima, with the title inside, was found Sunday around 4 a.m. ET, on a nearby property owned by the Dinardos, Weintraub said in a news release. Also found in the Nissan was Meo's insulin kit for treatment of his diabetes, which the the district attorney said he "never went anywhere without."

Weintraub said a number of sites are now under investigation.

What we don't know:

The fate of Meo and the other two missing men remains a mystery. More human remains were found inside the common grave, but their identity was not immediately known.

Are there any suspects?

What we know:

No one has been charged in Finocchiaro's death or the disappearance of the other men.

Cosmo Dinardo, 20, was arraigned via video before Magisterial District Judge Maggie Snow on one count each of theft by unlawful taking and receiving stolen property, both third-degree felonies. (Bucks County DA via CNN)

Police arrested the son of the property owners, Cosmo Dinardo, 20, of Bensalem Township in Bucks County, on Wednesday afternoon for stealing and attempting to sell Meo's car. Dinardo tried to sell the car to a friend for $500, a criminal affidavit states.

The keys and vehicle title, which had not been legally exchanged, were folded up and hanging on the wall inside the garage of the property, the affidavit states. Dinardo faces one count each of theft and receiving stolen property. His bail was set at $5 million cash after Weintraub argued he was a flight risk.

Dinardo had been arrested Monday on a charge of possession of a firearm, an offense dating to February unrelated to the missing men, Weintraub said. He was prohibited from possessing a firearm because he had a mental illness and had been involuntarily committed to a mental institution for inpatient care, court documents said.

Dinardo's father paid 10% of his $1 million bail in cash, and he was released Tuesday evening.

What we don't know:

It's not known whether Dinardo and any of the four missing men knew one another before this incident.

Authorities have not named suspects in this case.