"I am very relieved to say we brought four young men one step closer to their loved ones so they can rest in peace".
Prosecutors further revealed they were led to the DiNardo farm after pinging one of the missing men's cellphones.
Here's what we know about the mysterious disappearances and the investigation that has consumed this suburban community and riveted the nation.
The victims are 19-year-old Dean Finocchiaro, 22-year-old Mark Sturgis, 21-year-old Tom Meo and 19-year-old Jimi Taro Patrick.
DiNardo then burned the bodies - three of them inside a drum - at his family's farm in Solebury Township, about 30 miles (48 kilometers) north of Philadelphia, the person said.
Authorities have said they're looking at pursuing homicide charges against a 20-year-old man who was taken into custody Wednesday. When Meo and Sturgis got out of the vehicle, DiNardo claims he shot Meo in the back - then shot Sturgis who was trying to run away. On Saturday, they got a break: Mr. Finocchiaro's cellphone was tracked to the farm in Solebury Township, where they found Mr. Meo's vehicle.
As police led the handcuffed suspect to a van Thursday evening, DiNardo said "I'm sorry" when asked by reporters whether he had sympathy for the victims' families. DiNardo said he then drove a backhoe that was on the property to where Patrick lay, dug a hole no more than 6 feet deep and buried his body, according to the court documents. Kratz shot Finocchario, and DiNardo placed him in a metal tank.
DiNardo and Kratz have each provided statements to investigators, and DiNardo has described Kratz as his cousin, according to the district attorney's office. DiNardo admitted to killing Patrick after he didn't have the $8,000 he agreed to pay for four pounds of marijuana.More news: New Zealand battle for the last semi-final spot
Cosmo DiNardo and Sean Kratz were charged Friday with the slayings of four men who were killed on a farm in Solebury Township. DiNardo sold quarter-pound quantities of marijuana for several thousand dollars and sold handguns to area residents, the person said.
In his confession, Dinardo detailed a series of shocking killings with no clear motive.
DiNario responded: "I mean I know the kid but yeah I feel bad for his parents". "In exchange for that confession, Mr. DiNardo was promised by the district attorney that he will spare his life by not invoking the death penalty".
DiNardo is said to be unsafe and have schizophrenia, according to the BBC.
Patrick, who was a year behind DiNardo at a Catholic high school for boys, was last seen on July 5, while the other three vanished two days later. But Kratz told police that Dinardo was the one who shot Finocchiaro.
Dinardo had been arrested on Monday at his home for owning a gun he was not allowed to possess because he had previously been involuntarily committed to a mental health facility, prosecutors said.
Dinardo was released on bail on Tuesday when his father paid 10% of the $1 million bail in cash.
That same night, DiNardo said, he met Meo and Sturgis together at a parking lot in Peddlers Village. The charging documents state that DiNardo used a backhoe to pick up both men's bodies, put them in the same metal tank as Finocchiaro and poured gasoline into the metal tank and lit it.