Cole Tomas Allen, already facing a maximum life sentence on charges of attempting to assassinate President Donald Trump, now faces an additional federal assault count after prosecutors formally alleged he fired a shotgun that struck a Secret Service officer during the chaotic breach of the White House Correspondents’ Association dinner last month. The indictment, returned Tuesday by a grand jury in Washington, D.C., adds a charge of assaulting a federal officer with a deadly weapon to the three counts Allen faced in an initial criminal complaint — meaning prosecutors now accept that a single gunshot that hit the officer in a bullet-resistant vest came from Allen’s weapon.

According to court filings and statements from law enforcement, Allen, of Torrance, drove to the Washington Hilton on April 25 and ran through a security checkpoint outside the high-profile dinner, where President Trump was scheduled to deliver remarks. Carrying a shotgun and knives, he pointed his weapon at a Secret Service officer; the officer fired five rounds but missed, authorities said. Allen was injured in the ensuing struggle but was not shot. The officer was struck once in the vest and later recovered. The incident forced an early end to one of Washington’s most prominent annual events.

Allen’s attorneys have mounted a vigorous defense, questioning the government’s central theory. “In sum,” they wrote in a court filing, “the government’s entire argument about the nature and circumstances of the offense is based upon inferences drawn about Mr. Allen’s intent that raise more questions than answers.” The attorneys have not detailed their own alternative account but have signaled that key issues of intent and the source of the gunshot are unresolved.

Acting Attorney General Todd Blanche acknowledged last week that investigators wanted to examine additional ballistics evidence before concluding that Allen fired the shot that struck the officer. Tuesday’s indictment, which includes that conclusion as a formal charge, suggests that review has been completed. If convicted on the new assault count, Allen would face an additional sentence of up to 20 years beyond any penalty for the existing charges.

Separate court records detail Allen’s treatment after his arrest. He was placed on suicide watch in a federal jail, where his attorneys have complained that he was unnecessarily confined in a padded room with constant lighting, repeatedly strip searched, and placed in restraints outside his cell. Jail officials lifted the suicide watch over the weekend, according to court documents. Allen remains in custody pending further proceedings.