WASHINGTON (AP) — Authorities have determined that buckshot from the gun of the man charged with trying to storm the White House Correspondents' Association dinner in an attempt to kill President Donald Trump struck a Secret Service agent, according to the federal prosecutor overseeing the investigation.

Jeanine Pirro, the U.S. attorney for the District of Columbia, said last week there was no evidence the agent was hit by friendly fire during the incident at a Washington hotel on April 25, but she went beyond that Sunday in saying a shot from one of Cole Tomas Allen's weapons hit the officer's bullet-resistant vest.

“We now can establish that a pellet that came from the buckshot from the defendant’s Mossberg pump-action shotgun was intertwined with the fiber of the vest of the Secret Service officer,” she told CNN's “State of the Union.” “It is definitively his bullet."

Allen, who remains behind bars for now pending his trial, was injured during the attack but was not shot. The officer survived.

On Thursday, Pirro posted a video on social media showing the moment that authorities say a man with guns and knives attempted to storm the media gala. Questions have lingered about whose bullet struck the officer as the suspect ran through security with a long gun toward the ballroom packed with journalists, administration officials and others.

A phone call to lawyers representing Allen went unanswered on Sunday.

Allen has been charged with attempted assassination of the president, as well as two additional firearms counts, including discharging a weapon during a crime of violence. He faces up to life in prison if convicted of the assassination count alone.

Allen, 31, is from Torrance, California. He worked as a part-time tutor for a test preparation company and is an amateur video game developer.