Thomas Matthew Crooks, the shooter who attempted to assassinate former President Donald Trump at a rally in Butler County, Pennsylvania, told his boss he needed Saturday off for a personal matter.

He assured coworkers he’d return on Sunday. Investigators have yet to determine Crooks’ motive but are piecing together his activities.

By 3 p.m., about three hours before the shooting, Crooks was seen at the rally’s security screening area with a rangefinder, which raised security personnel’s suspicion. After leaving the area, it’s believed he retrieved a rifle from his car.

Witnesses later reported seeing Crooks on the roof of the American Glass Research building, where he was observed using the rangefinder to look at counter-sniper teams.

He had climbed onto the rooftop by scaling the building’s air conditioning system, CNN has reported.

After the shooting, law enforcement found a bulletproof vest, three loaded magazines, and two remote-controlled explosive devices in Crooks’ car.

At his residence, they discovered another bulletproof vest, an additional explosive device, and a 3D printer.

Over the past several months, Crooks had received multiple packages, some marked as potentially hazardous, according to an FBI and Department of Homeland Security bulletin.

Written by B.C. Begley