The Aug. 4 attack, which ended when police shot and killed 24-year-old Connor Betts, was one of three-high profile mass shootings over three weeks that stunned the United States and stoked its long-running debate on gun rights.
Police have said there was nothing in his background that would have prevented him from buying the AR-15 style gun used in the shooting.
The FBI said last week that Betts, had a history of violent obsessions and had mused about committing mass murder before his rampage in Dayton's historic downtown.
Federal investigators spoke to him again on August 8, and "Kollie indicated he and Betts had done 'hard drugs, ' marijuana and acid together four to five times a week during 2014 to 2015", reads the statement.
One of the suggestions for new laws that's gained steam in recent days is known as "lie and try", and it would encourage more prosecutions of people who attempt to buy a firearm knowing they are banned buyers.More news: Realme 5 Series India Launch Set for August 20
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Kollie had a concealed carry permit and owned a micro Draco pistol, a Taurus semi-automatic and a.38 Taurus revolver, Glassman said.
The agents, while talking to Mr. Kollie at his Kettering, Ohio, residence, smelled marijuana, saw drug paraphernalia and also spotted a pistol.
Kollie is facing up to 15 years in prison.
A search warrant was executed at Kollie's home, turning up several weapons, marijuana, and mushrooms.
According to the criminal complaint, Kollie stored the items in his apartment "to assist [the gunman] in hiding them from [the gunman's] parents". He was also charged with possession of a firearm by an unlawful user of a controlled substance, according to court documents.
Authorities say more information about the charges being unsealed against the unnamed person will be announced Monday afternoon.