Then on Wednesday, authorities arrested DiNardo on charges he tried to sell Meo's 1996 Nissan Maxima a day after he was last seen.
On Tuesday, county District Attorney Matthew Weintraub confirmed authorities are concentrating on the farm as the search continues for Mark Sturgis, 22; Tom Meo, 21; Dean Finocchiaro, 19; and and Jimi Tar Patrick, 19.
Lang says Cosmo DiNardo has pleaded guilty to four counts of first degree murder.
"This is a homicide, make no mistake about it", Weintraub said.
Officials said there were signs some or all of the men knew one another and were working to discover their links. Dinardo says he burned the bodies and was assisted by a 20 year old Northeast Philadelphia man, who is now behind bars, his name has not been released. Those remains have yet to be identified. This is the second man connected to the case.
His parents still remain in custody on $5 million cash bail over a gun possession charge and trying to sell one of the victim's cars.
The area had been in the grips of panic after four men disappeared in the span of three days last week.More news: Watch: Arsenal's Club Record Signing,lacazette score on his debut
Asked what he wanted to say to the families of the men as he was escorted from court on Thursday, a handcuffed DiNardo said: "I'm sorry".
Early Thursday morning, the human remains of 19-year-old Dean Finocchiaro was found in a 12.5 deep common grave at farm in Solebury Township, Pennsylvania.
One of the men disappeared on Wednesday and three others on Friday.
"As is often the case in an investigation of this magnitude, it is all hands on deck", Weintraub said.
Newtown Township, Plumstead Township, Middletown Township Police and state police are all involved in the joint investigation, Bucks County Assistant District Attorney Gregg Shore told ABC affiliate WPVI-TV.
DiNardo has told investigators where the rest of the bodies are.
"I don't understand the science behind it, but those dogs could smell these poor boys 12½ feet below the ground", Weintraub said at a midnight news conference.
The Times reports that police searched DiNardo's home in Bensalem, which is about 30 miles from his parents' property. DiNardo was accused of illegally possessing a shotgun and ammunition after being involuntarily committed to a mental institution.