Arizona man sold firearms to undercover FBI agent for mass shooting, indictment says

PHOENIX — A firearms dealer in Arizona sold guns to an undercover federal agent he believed would help him carry out his plan for a mass shooting targeting minorities, an attack he hoped would “incite a race war,” according to an indictment of the federal grand jury.

Mark Adams Prieto was indicted Tuesday by an Arizona grand jury on charges of trafficking in firearms, transferring a firearm for use in a hate crime, and possession of an unregistered firearm.

Court records did not list an attorney who could comment on Prieto’s behalf. An attorney who briefly represented Prieto after he was arrested in neighboring New Mexico last month did not respond to a request for comment Wednesday.

According to the indictment, the 58-year-old from Prescott, Arizona, recruited the undercover FBI agent and an informant at a gun show where Prieto was a vendor.

According to the indictment, Prieto told them that he had been considering carrying out a mass murder of minority groups to “spark a race war” ahead of the November presidential election. Prieto later identified a rap concert in Atlanta in mid-May as the trigger for the attack, the complaint alleges.

The indictment says the planning for the shooting began in January and took place over several months at gun shows in Arizona, including in Phoenix and Tucson. During the gun shows, the indictment alleges, Prieto sold two guns for use in the shooting to the FBI agent.

Prieto was arrested in New Mexico on May 14 – around the time of the Atlanta concert – while driving east from Arizona. Authorities said they found seven firearms in his vehicle.

After his arrest, court records show, a U.S. district judge in New Mexico ordered Prieto to remain in federal custody, saying the “severity of the danger to the community is extreme” if he were released.