Charles Lawson approached two police officers in the Pentagon parking lot at 3:30 p.m. on Aug. 6 and made incoherent statements, investigators said.
He admitted to having a weapon in his car when questioned and also to having spent the day drinking alcohol, WTOP reported Monday, citing court documents.
Police handcuffed Lawson and searched his vehicle. They discovered a loaded 12-gauge shotgun, a box of shotgun shells, an 18-inch machete and a pocketknife in his pickup truck, as well as an open bottle of whiskey and white paper with a "green leafy substance" wrapped inside, according to court documents.
Lawson told police he had driven overnight from Pineville, Ky., stopping only for gas.
Police took Lawson to the hospital for evaluations, where he commented to a doctor about being diagnosed as a schizophrenic, court documents said.
Lawson had been involuntarily hospitalized in November 2018 for mental illness, a background check found, and he cannot legally have a gun.
Lawson is facing a federal charge of unlawfully possessing a firearm after being previously committed to a mental institution.