An Arizona man has been arrested for planning a mass shooting in Atlanta targeting African Americans, Jews, or Muslims specifically to start a race war.

Mark Adams Prieto allegedly sold rifles at gun shows, often “off book,” and discussed his plans to start a race war ahead of the presidential election in November, the US Department of Justice said.

Prieto, 58, was indicted by a federal grand jury on Tuesday on charges of firearms trafficking, transfer of a firearm for use in a hate crime, and possession of an unregistered firearm. According to the indictment, Prieto discussed his plans with two people between January and May this year, believing that the two people, who were working with FBI, “shared his racist beliefs and wanted to commit a mass shooting to incite a race war.”

The plan, the DOJ said, was to target a concert in Atlanta in mid-May. During the planning stages, Prieto, a gun-show vender, sold an AR- and an AK-style rifle to one of the people. He was arrested on May 14 driving east on Interstate 40 in New Mexico. He had seven rifles in his vehicle when he was taken into custody, and a search warrant executed at his home in Prescott, Arizona, found multiple firearms, including an unregistered short-barreled rifle.

An affidavit filed with the indictment says the investigation began in October 2023 when a source told law enforcement about Prieto’s plans, WSB reported. The source said they’d spoken with him several times at gun shows over several years, but his comments in the past year became “suspicious and alarming” and included “advocating for a mass shooting, and specifically yargeting ‘Blacks, Jews or Muslims.'”

“Prieto believes that martial law will be implemented shortly after the 2024 election and that a mass shooting should occur prior to the implementation of martial law,” the source said, adding that Prieto asked if they were “ready to kill a bunch of people.”

The source and undercover agents met with Prieto at a gun show in January, first only making “small talk.” The next day he went into details about his plans:

“The reason I say Atlanta. Why, why is Georgia such a [expletive]-up state now? When I was a kid that was one of the most conservative states in the country. Why is it not now? Because as the crime got worse in LA, St. Louis, and all these other cities, all the [expletives] moved out of those (places) and moved to Atlanta. That’s why it isn’t so great anymore. And they’ve been there for a couple, several years.”

As the months went on, Prieto continued to talk about his plans to carry out the attack before the presidential election because after, “they might hae everything in place you can’t even drive, you’ll be stopped,” he reportedly said.

Prieto’s plans for an attack in Atlanta in mid-May — at the city’s State Farm Arena — were reportedly pushed back to June. He was allegedly en route to visit his mother in Florida when he was arrested with a vehicle full of guns.

No trial date has been set, but each conviction for trafficking carries a maximum of 15 years in prison and a fine of $250,000. The unregistered firearm charge carries an maximum of 10 years in prison and a fine of $250,000. It’s not clear what the hate crime enhancement would do to a potential sentence.

For the latest true crime and justice news, subscribe to the ‘Crime Stories with Nancy Grace’ podcast.

[Featured image: Mark Adams Prieto/US Attorney’s Office for the District of Arizona]