WASHINGTON, D.C. — U.S. Attorney for the District of Columbia Jeanine Pirro announced that prosecutors have linked shotgun pellets from an alleged assassination attempt at the White House Correspondents' Association dinner to the vest of a Secret Service officer. She said a grand jury is likely to convene later in the week to consider additional charges against the suspect, Cole Tomas Allen, 31.

"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," Pirro said. The forensic finding gives the U.S. government evidence that a federal agent was shot during the attack. "There's no question that once we get into the grand jury there will be many, many more charges," she said.

Allen was charged last week with three federal crimes, including attempting to assassinate the president. He allegedly ran past a security checkpoint at the Washington Hilton hotel, where the annual dinner was being held, and fired a shotgun outside the doors leading into the ballroom. Inside, the U.S. president, First Lady Melania Trump and several senior cabinet members had gathered along with hundreds of journalists and their guests.

According to legal filings from last week, Allen traveled by train from California to Washington armed with a shotgun, a .38-caliber pistol, knives and daggers in order to carry out the attack. Prosecutors wrote in the filing: "Allen was willing to commit a mass shooting inside a room full of the highest-ranking officials in the U.S. government."

Allen had shared social media posts comparing Trump to Adolf Hitler and encouraged others critical of his presidency to purchase guns. He allegedly sent a document to family members before the attack in which he criticized Trump administration policies and the security at the Washington Hilton hotel. In the same document, Allen apologized to his family for his actions.