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 three-time 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,

The man, Jeffrey Michael Kelly, 60, was arrested Tuesday, according to the authorities. Mr. Kelly also set out anti-Democratic Party signs lined with razor blades near his home, attaching bags filled with an unknown white powder and labeled “Biohazard,” according to court papers.