Trump Agrees to Be Interviewed by F.B.I. in Its Investigation Into Gunman

Former President Donald J. Trump has agreed to be interviewed by the F.B.I. as part of its investigation into the motives of the 20-year-old man who tried to assassinate him during a campaign rally in Pennsylvania on July 13, bureau officials said on Monday.

“We want to get his perspective on what he observed, like any other witness,” Kevin Rojek, the head of the bureau’s Pittsburgh field office, said on a call with reporters. “It is a standard victim interview, like we would do.”

Mr. Trump’s supporters had sharply criticized Christopher A. Wray, the bureau’s director, for telling a House committee last week that investigators had not definitively determined the cause of the minor injury to the former president’s ear. By week’s end, the F.B.I. offered its most definitive explanation yet, saying it was a bullet or a fragment of one, a statement it reiterated on Monday.

The F.B.I. also provided the most comprehensive portrait to date of the gunman, Thomas Crooks, revealing that he carefully concealed more than two dozen online purchases of weapons and explosives using aliases, and that he gathered information on other assassination attempts, including the shooting of Robert Fico, the prime minister of Slovakia, in May.

Mr. Rojek also revisited a lost opportunity to stop Mr. Crooks. He said that a local law enforcement officer who was boosted onto the warehouse roof where Mr. Crooks had positioned himself just before the shooting “dropped down” to the ground after the shooter aimed at the officer.

About 25 to 30 seconds later, Mr. Crooks fired eight rounds — hitting Mr. Trump’s ear, killing a bystander and injuring two other people.

F.B.I. officials said they were taking the unusual step of providing investigative details, even