On Tuesday, a federal grand jury indicted Arizona resident Mark Adams Prieto, charging him with firearms trafficking, transfer of a firearm for use in a hate crime, and possession of an unregistered firearm. According to authorities, Prieto was planning to stage a mass shooting at a a Bad Bunny concert in Atlanta, hoping to start a race war ahead of this year’s presidential election.

The FBI arrested Mark Adams Prieto last month after investigating him for months, as NBC News reports. Last October, an informant told the FBI that 58-year-old Prieto had plans to incite a race war. The informant allegedly talked to Prieto at gun shows over several years — Prieto was a vendor — and claims that Prieto repeatedly endorsed the idea of a mass shooting targeting Black people, Jews, and Muslims. The FBI kept Prieto under surveillance for months, and he allegedly tried to recruit the informant and an undercover FBI agent to help him with a mass shooting at an Atlanta rap concert while selling them guns. Prieto allegedly figured that there would be a lot of Black people at an Atlanta show, and he wanted to put up a high body count and leave Confederate flags behind as a message.

According to the informant, Prieto planned to carry out his attack at one of two Bad Bunny concerts at Atlanta’s State Farm Arena last month. Per NBC, “Prieto told the undercover agent that he wanted them to wear hoodies, according to the affidavit, because he believed no one was going to be suspicious about someone wearing a hoodie at a rap concert.” (Prieto also allegedly considered pushing back the shooting to something later in the summer, though it’s not clear when or where.)

The FBI arrested Prieto on the New Mexico Interstate on May 14, the date of the first Bad Bunny show. During the arrest, he admitted to discussing plans for such an attack but said that he didn’t actually plan to proceed with the shooting. Prieto apparently admitted to selling an AR-15 to an undercover agent, telling the agent that the gun would be good to use in such an attack. During a search of Prieto’s home, agents also found an unregistered short-barreled rifle.