Crooks used an AR-style rifle, which authorities said was purchased legally by his father. Investigators also found he brought multiple loaded magazines. He also bought 50 rounds on the day of the shooting. Authorities found a bulletproof vest in his car and another rudimentary explosive device at his home. Over the past few months he had received several packages there, including some that had potentially hazardous material.

Loading

The shooting raised serious questions about why law enforcement was unable to stop the man from getting on a roof and opening fire. Multiple investigations into the security failures are under way, including a Department of Homeland Security inspector general’s probe into the Secret Service’s handling of security.

The Republican chairman of the House oversight and accountability committee issued a subpoena on Wednesday to Secret Service Director Kimberly Cheatle for her to appear before the committee on Monday. Republicans have been calling for Cheatle to resign following the shooting, although she has said she has no intention to do so.

Local law enforcement had noticed Crooks pacing around the edges of the rally, shouldering a big backpack and peering into the lens of a rangefinder toward the rooftops behind the stage where the former US president later stood, officials have told the Associated Press.

An image of Crooks was circulated by officers stationed outside the security perimeter. Witnesses later saw him climbing up the side of a squat manufacturing building that was within 135 meters of the stage. He then set up his AR-style rifle and lay on the rooftop, a detonator in his pocket to set off crude explosive devices that were stashed in his car parked nearby.

Butler Township manager Tom Knights said in a statement on Thursday that officers were searching for a suspicious person around the time Trump arrived. Officers didn’t find him around the building, so a Butler Township officer attempted to gain access to the roof by being hoisted up by another officer, Knights said. The officer spotted a person on the roof, and that person pointed a rifle at the officer, Knights said.

“The officer was in a defenceless position, and there was no way he could engage the actor while holding onto the roof edge,” Knights said. The officer fell to the ground and Butler Township officers “immediately communicated the individual’s location and that he was in possession of a weapon,” Knights said.

Moments later, Crooks started firing, sending panicked spectators ducking for cover as Secret Service agents shielded Trump and pulled him from the stage. Two counter-sniper teams were stationed on buildings behind Trump, and the team further away from Crooks fired once, killing him.