He was released after his father paid a bond but then rearrested on 12 July accused of stealing and trying to sell a auto, found on the farm, belonging to Mr Meo.
Although the motive remains a mystery, all four men died meeting with the accused killer to buy marijuana.
Paul Lang, DiNardo's lawyer, told reporters earlier Thursday DiNardo, 20, is ready to plead guilty four counts of first-degree murder.
In exchange for his full confession, DiNardo will be spared the death penalty, Lang said.
"I can't predict the future, but that is what I believe", Weintraub said. "In addition, we gained very, very valuable intelligence and information that we did not have. which allowed us to be able to charge co-defendant Sean Kratz".
Prosecutors indicated DiNardo had been diagnosed with schizophrenia.
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.
"I'm sorry", said DiNardo (r.) as he was led out of the Bucks County Justice Center in handcuffs and an orange jumpsuit.. Text messages shared by an unidentified source involved in a conversation with DiNardo on the app Snapchat revealed the 20-year-old's apparent lack of concern for the missing boys.
All the victims were buried on a farm property in Solebury, Pennsylvania, owned by DiNardo's parents.
Inside the farm, investigators have been at work digging deep into the ground.
"We're not going to rest until we get through every inch of that property", Weintraub said, according to The Associated Press. The FBI has sent an evidence response team to help with the investigation and is helping local detectives manage incoming tips.
The 90-acre (0.14-square-mile) property in Solebury Township has been scoured by law enforcement agencies, heavy construction equipment and cadaver dogs.
DiNardo's parents declined to comment after leaving a government building where he spent several hours with Bucks County District Attorney Matthew Weintraub and other investigators.
The other missing men are 22-year-old Mark Sturgis, 19-year-old Dean Finocchiaro and 19-year-old Jimi Tar Patrick. The Bucks County District Attorney said early this morning that one set of remains has been identified as 19 year old Dean Finochiaro.
21-year-old Tom Meo, 22-year-old Mark Sturgis, and Finocchiaro were last seen on July 7. The two are described as good friends. Dinardo picked up Kratz, his cousin, and the two drove to Finocchiaro's house and planned to rob him, the affidavit states. An affidavit in that case said he is "known to be suffering from mental illness".
In May, his last scheduled hearing was postponed because he had "medical issues", according to court records. That only added to the speculation and rumors before DiNardo's confession.
The next day, Meo's mother reported him missing.
The details were provided after one of Cosmo DiNardo's lawyers said Thursday that DiNardo had confessed to murdering the missing men, who included a Maryland college student, and had told investigators where their bodies were.
The police authorities then ordered the research on all the properties of the torque, in order to find clues that may lead to the four men that it was now no news since five days.
Later the same day, DiNardo picked up Meo and Sturgis. Officials say Meo could not survive without the kit.
The prosecutor, who has held twice-daily briefings, made it clear Thursday he knew a lot more than he was saying, citing the need to protect the investigation. The body was later found Thursday by investigators.
Meo collapsed, screaming, and Sturgis attempted to run away when DiNardo allegedly began shooting at him, too.