Arizona Man Plotted Mass Shooting to Trigger ‘Race War,’ Officials Say

An Arizona man who planned to commit a mass shooting at an Atlanta rap concert as a way of inciting a “race war” has been indicted by a federal grand jury on hate crime and firearm charges.

The man, Mark Adams Prieto, hatched a plan in several discussions with two people working with the F.B.I. who posed as racist extremists to carry out a mass shooting targeting Black people and other people of color at a concert in Atlanta on May 14 and May 15, the Justice Department said on Tuesday.

Mr. Prieto intended for the shooting to incite a “race war” before the presidential election, prosecutors said in a news release.

Mr. Prieto, 58, was reported to the authorities last year by an acquaintance who said he had made concerning comments calling for mass shootings targeting Black people and others, according to officials.

Mr. Prieto faces two counts of trafficking in firearms, one count of transfer of a firearm for use in a hate crime and one count of possessing an unregistered firearm.

He faces a maximum 15-year prison sentence for each firearm trafficking and transfer charge and a maximum 10-year sentence for the unregistered firearm charge, prosecutors said. Mr. Prieto also could be fined $250,000 for each count.

A lawyer for Mr. Prieto was not listed in a court database as of Saturday evening.

Officials stopped and arrested Mr. Prieto, of Prescott, Ariz., near Route I-40 in New Mexico on May 14, according to prosecutors.

He had seven firearms in his vehicle, and investigators carrying out a search warrant would later find an arsenal of guns in his home, including an unregistered short-barreled rifle and AR-15 and AK-47-style rifles, according to the indictment.

Officials were tipped off about Mr. Prieto in October by a man who had known and frequently chatted with him at gun shows, according to an affidavit filed in court.

The man told the authorities that Mr. Prieto began making alarming comments, “including advocating for a mass shooting, and specifically targeting ‘Blacks, Jews or Muslims,’” the affidavit said.

The indictment said that beginning in January, at several gun shows around Arizona, Mr. Prieto discussed mass shooting plans with an undercover agent and the man who had reported him (now working as an informant).

In a conversation at a gun show on Jan. 21, Mr. Prieto asked the men for their help carrying out a mass shooting at a rap concert in Atlanta, where he believed there would be a large number of Black concertgoers.

Mr. Prieto suggested they leave behind Confederate flags at the attack site and shout things like “Black lives don’t matter, white lives matter,” to make clear the shooting was racially motivated, according to the affidavit.

Over the course of several gun show meetings in February, March and April, Mr. Prieto expounded on tactics and how to effectively use their weapons in the attack. During that time, he sold the undercover agent firearms, according to the affidavit, and confirmed that the attack would take place at a concert at State Farm Arena on May 14 or 15.

Bad Bunny, one of the biggest names in Latin American music, went on to hold concerts at that venue on those dates.

As May approached, Mr. Prieto suggested pushing back the attack date to June or July, emphasizing that it should be done before the election in November. In May, he said he planned to travel to Atlanta to conduct reconnaissance around the arena.

He initially told investigators that he had been traveling to Florida to visit his mother, according to the affidavit. He later confessed to the authorities about the planned attack but said that he did not intend to go forward with it.