(CNN) — Arizona investigators surveilling the man accused of shooting at the Democratic National Committee office in a suburb of Phoenix saw him posting political signs with bags of a white, powdery substance attached,

An Arizona prosecutor said the man arrested in the shooting of a Democratic National Committee office in suburban Phoenix had more than 120 guns and over 250,000 rounds of ammunition in his home, leading law enforcement to believe he may have been planning a mass casualty event.

Arizona investigators surveilling the man accused of shooting at the Democratic National Committee office in a suburb of Phoenix saw him posting political signs with bags of a white, powdery substance attached,

The suspect is accused of hanging offensive political signs lined with razor blades in other parts of the battleground state

Authorities searching the home of a 60-year-old man accused of shooting at a Democratic National Committee office in Tempe, Arizona, discovered an extensive collection of weapons — including 120 guns,

No one was in the office during the shootings and there were no casualties. Police said Kelly fired BB pellets and then gunshots at the glass door and window of the DNC field office in the early hours of Sept.