The F.B.I. said on Friday that Donald J. Trump had been struck by a “bullet, whether whole or fragmented into smaller pieces,” providing the most definitive explanation to date about what injured the former president’s ear during an assassination attempt this month.
Ambiguity about Mr. Trump’s injury turned into a political firestorm as the former president and his political allies attacked the F.B.I. director, Christopher A. Wray, for comments he made on Wednesday before Congress.
“With respect to former President Trump, there’s some question about whether or not it’s a bullet or shrapnel that hit his ear,” Mr. Wray told the House Judiciary Committee.
Mr. Wray’s comments incensed Mr. Trump because they seemed to cast doubt on the former president’s version of what happened at a July 13 campaign rally in Butler, Pa., when a gunman opened fire, killing one and injuring two others. The shooter, Thomas Crooks, 20, was killed by a Secret Service sniper.
Mr. Trump has maintained that he narrowly escaped death or serious injury after a bullet bloodied his ear, and that divine intervention spared his life. Mr. Wray’s suggestion that it might have been shrapnel angered him.
After Speaker Mike Johnson questioned Mr. Wray’s comments on Thursday, the F.B.I. said in a statement that it was examining bullet fragments, and law enforcement officials said the bureau was trying to determine whether it was a bullet or a piece of one.
Mr. Trump, who has been deeply critical of the F.B.I. for years, responded with a blistering post on social media: “No, it was, unfortunately, a bullet that hit my ear, and hit it hard. There was no glass, there was no shrapnel.”
He added, “No wonder the once storied FBI has lost the confidence of America!”
Mr. Wray has never disputed that the former president was in grave danger. He has repeatedly said the assassination attempt was an attack on democracy, and his agency said on Friday that there was no doubt that Mr. Crooks tried to kill the former president.
“What struck former President Trump in the ear was a bullet, whether whole or fragmented into smaller pieces, fired from the deceased subject’s rifle,” the F.B.I. said in a statement.
Mr. Crooks fired eight bullets from an AR-15-style semiautomatic rifle. Gun experts say the ammunition that Mr. Crooks used can easily fragment after hitting a solid object, sending deadly debris through the air. In certain circumstances, shrapnel and bullet fragments can be lethal.
On Friday, The New York Times published an analysis that strongly suggested Mr. Trump was grazed by the first of the eight bullets fired by the gunman.