According to the U.S. attorney's office for the Southern District of Texas, Ajay Dhingra of Houston initially came under U.S. Secret Service scrutiny when he sent the missive in August.
Dhingra had previously been committed to a psychiatric facility and was banned from owning firearms, and when federal agents showed up at his home, he told them he'd been diagnosed with schizophrenia, according to court documents.
While at the home, agents found a handgun and an AR-15 rifle outfitted with a bump stock — a device that allows semi-automatic firearms to be fired rapidly, machine-gun style. They also found four 100-round magazines.
The national bump stock ban became active in March under the same federal law that bans possession of machine guns. The devices came under scrutiny after they were used in a 2017 mass shooting that killed 58 people in Las Vegas.