The gunman in the attempted assassination of former President Trump is believed to have flown a drone around the Pennsylvania rally site ahead of time in an apparent attempt to scope out the site before the event, a law enforcement official said Saturday.

The drone has been recovered by the FBI, which is leading the investigation into last Saturday’s shooting at the rally by 20-year-old Thomas Matthew Crooks.

Crooks fired multiple rounds from the roof of a building adjacent to the Butler Farm Show grounds, where Trump was speaking, before being fatally shot by a Secret Service countersniper. The existence of the device and its use at some point before the shooting could help explain why Crooks knew to fire from the point.

The official who described the drone was not authorized to discuss the matter publicly and spoke to the Associated Press on the condition of anonymity. Details of the drone were first reported by the Wall Street Journal.

Trump said this week that one bullet clipped his right ear. A memo released Saturday by the Trump campaign and authored by U.S. Rep. Ronny Jackson (R-Texas), who served as the GOP nominee’s White House physician, said that Trump sustained a gunshot wound to the right ear from a high-powered rifle that came “less than a quarter of an inch from entering his head, and struck the top of his right ear.”

One of the bullets aimed toward Trump killed 50-year-old firefighter Corey Comperatore, a spectator who was in the bleachers. Two others were seriously wounded.

The FBI is continuing to investigate what may have motivated Crooks to carry out the attack. So far, officials have not found any ideological bent that could help explain his actions.

Investigators who searched his phone found photos of Trump, President Biden and other senior government officials, and also found that he had looked up the dates for the Democratic National Convention as well as Trump’s appearances. He also searched for information about major depressive disorder.

More details about the investigation are expected to be made public in the coming week when FBI Director Christopher A. Wray appears before the House Judiciary Committee.

Tucker writes for the Associated Press. AP writer Jill Colvin contributed to this report.