Kelly has since been charged with unlawful discharge, shooting at a non-residential structure, terrorism, and criminal damage. He is also accused of "hanging suspicious bags of white powder from several political signs lined with razor blades," according to KVXN.

The Democratic field office was targeted in three separate shootings on September 16, September 23 and October 6. Witnesses reported a silver Toyota Highlander SUV near the scene. No one was in the office at the time of the shootings, and no deaths or injuries were reported in either incident.

According to Phoenix-based outlets KTVK and KPHO, Kelly allegedly used Google Maps to search the location of the field office, and he was also reportedly seen posting "anti-Democratic ideology signs" in several locations near his home.

KVXN further reported that when the Bureau of Alcohol, Tobacco and Firearms searched Kelly's home, they found a massive arsenal of weapons, including 120 firearms, approximately 250,000 rounds of ammunition and a grenade launcher, in addition to body armor. Maricopa County Deputy County Attorney Nena Bhatia said it's likely Kelly was planning a mass shooting.

"The state and law enforcement believe that this person was preparing to commit an act of mass casualty with the guns he had, and that his progression of violence was escalating," she said.

While the types of guns and caliber of ammunition investigators seized have not yet been disclosed, it's worth noting that an AK-47 in its fully automatic setting is capable of firing 600 rounds a minute. This means that without even counting for time to reload, it would take approximately seven hours to fire 250,000 rounds of ammunition continuously.

Kelly is currently being held on a $500,000 bond, according to the Maricopa County Sheriff's Office. His next court appearance is scheduled for Tuesday, October 29.