Police were initially uncertain about the connection between the four missing young men. They've since learned Patrick and DiNardo were friends on Facebook, and apparently attended the same high school together a year apart in grade. A friend of DiNardo's claimed:
I’ll tell you that he was normal up until last year. He was in a quad accident and hit his head and was stranded for a day or so with a brain bleed. He had frontal lobe damage.
Police claim DiNardo has exhibited violent tendencies in the past. He was arrested after the bodies were found and held on $5 million bail. Shortly thereafter, he confessed to "committing or participating" in all four murders:
In return for DiNardo's confession, the prosecution agreed not to pursue the death penalty. DiNardo also claims he had an accomplice; police have already arrested another suspect in connection with the murders. Though DiNardo has of yet given no motive for his actions, police have confirmed each murder was connected to drug transactions gone awry. It's possible none of the four men encountered each other before being killed.
DiNardo had previously been committed to a mental health facility, and thus, according to Pennsylvania state law, is not legally allowed to own a gun. He was arrested in February for possession of a shotgun, but was released in late May due to improperly filed paperwork. The paperwork had to be corrected and resubmitted, but by the time this was done the search for the four missing men had already begun.
H/T - Uproxx, Philly.com