ATLANTA — An Arizona man was arrested in May for planning a mass shooting in Atlanta targeting African Americans in the city to incite a race war.

Mark Adams Prieto is accused of selling rifles to people to provide weapons to begin a race war ahead of the 2024 Presidential Election, according to the U.S. Department of Justice.

He was indicted Tuesday by a federal grand jury, following a months-long investigation by the Federal Bureau of Investigation and his arrest in mid-May.

An affidavit submitted in court by members of the FBI’s Joint Terrorism Task Force in Phoenix, Ariz. detailed how the investigation into Prieto began in October 2023.

According to the affidavit, a reliable source reported that a man later identified as Prieto “expressed a desire to incite a race war prior to the 2024 United States Presidential Election.”

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The affidavit says the source told FBI agents that they’d spoken to Prieto at various gun shows over three years, eventually including political conversation.

During the past year, Prieto’s comments became “suspicious and alarming,” according to the affidavit, “including advocating for a mass shooting, and specifically targeting ‘Blacks, Jews or Muslims.’”

The source told FBI agents that “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,” and asked the source in late 2023 if they were “ready to kill a bunch of people.”

The FBI said in the affidavit that this showed Prieto’s desire to recruit people to help him carry out an attack.

The investigation by federal agents found that Prieto worked as a gun show vendor in Prescott, Ariz., where he sold numerous firearms from his personal collection. The source told the FBI that Prieto also likes to conduct trades “off book” through cash or trade to “avoid possible issues or interactions with the Bureau of Alcohol, Tobacco, Firearms & Explosives.”

At the end of 2023, agents contacted the person running the Arizona-based Crossroads of the West gun shows, where Prieto was a vendor, who confirmed his status there, matching a description given to agents by their confidential source.

The FBI put Prieto under surveillance from January to March. At a gun show in mid-January, undercover agents met with Prieto and their confidential source.

While Prieto “only made small talk” with the source and undercover agents on the first day of the gun show, the next day, Prieto spoke about his plans for an attack, the affidavit says.

“Prieto divulged his plan to commit crimes of violence against African Americans in Atlanta, Georgia. Specifically,” Prieto told the source and undercover agents that he wanted their help to carry out a mass shooting at a yet-to-be-determined rap concert in the city, according to court documents.

According to court documents, that was when Prieto also explained why he wanted to carry out the proposed attack in Atlanta, saying:

“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.”

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He also said he wanted to perform the proposed attack at a rap concert because “there would be a high concentration of African Americans” at the event.

Part of the plan included leaving Confederate flags to send a message “that we’re going to fight back now, and every whitey will be the enemy across the whole country,” according to the affidavit.

Prieto also told the confidential source and undercover agents that he would show “no mercy, no quarter,” telling them that they could not “have any feeling, they’re not people. They’re monsters as far as I’m concerned.”

While under surveillance in February, the FBI saw Prieto go to a gun show in Phoenix, Ariz. While there, he was seen going into the gun show with two rifles and walking to the confidential source’s vendor booth. When he got to the booth, he “immediately” asked if the source and the undercover agent were still planning to participate in his attack, the affidavit says.

On multiple occasions, the affidavit notes that Prieto made it clear the attack was racially motivated, and that he wanted it to be explicitly “not a gang-related thing,” saying he planned to shout “KKK all the way,” among other slogans and emphasizing that having a high body count of victims was the most important part of his plan, according to court documents.

In February, he sold a firearm to the undercover agent for $2,000. Later, in March, undercover agents spoke to Prieto at his vendor table at a gun show, where he told them he still planned to commit the attack in Atlanta, saying that if they waited until after the presidential election, “they might have everything in place you can’t even drive, you’ll be stopped,” the documents say.

He later told the undercover agents that the targeted event would likely be a rap concert scheduled for State Farm Arena in midtown Atlanta for May 14 and May 15. Later plans involved pushing the attack back to sometime in June, according to USDOJ.

While traveling to Florida to visit his mother, USDOJ said officers stopped Prieto on Interstate 40 in mid-May.

“Prieto was stopped by law enforcement driving east from Arizona through New Mexico along Interstate 40. Prieto was in possession of seven firearms and was taken into federal custody.

Prieto Indicted for Firearms Trafficking and Possession : The suspect was identified in the security footage.