Cole Tomas Allen of Torrance, California, appeared Monday in the US District Court for the District of Columbia to face federal charges stemming from Saturday night’s armed assault on a security checkpoint at the White House Correspondents’ Dinner.

Magistrate Judge Matthew Sharbaugh ordered Allen held pending a detention hearing Thursday. The suspect, who appeared on a criminal complaint rather than an indictment, was not asked to enter a plea. He faces three federal counts: attempting to assassinate the president, transportation of a firearm in interstate commerce, and discharge of a firearm during a crime of violence.

Allen, 31, is a Caltech-trained mechanical engineer with a recent master’s degree in computer science from California State University, Dominguez Hills who tutored part-time at a Torrance test-prep company and built indie video games on the side, according to a WIRED review of public databases, which revealed a minimal online presence.

The Metropolitan Police Department claims that the suspect approached a Secret Service checkpoint at the Hilton on Saturday night armed with a shotgun, a handgun, and multiple knives. Agents intercepted the suspect before he could reach the ballroom, where President Donald Trump was preparing to speak.

Witnesses reported hearing several shots outside the room, and agents quickly moved Trump and Vice President JD Vance off the stage. One agent was hit but was protected by his bulletproof vest. Trump later told reporters the agent was unharmed.

MPD interim chief Jeffery Carroll characterized the suspect as a “lone actor” and said he was taken to a hospital for evaluation following his arrest.

Roughly 10 minutes before the shooting, the suspect allegedly emailed his family a “manifesto,” according to the New York Post, which cited two US officials and a copy of the document. In it, the author states they are “no longer willing to permit a pedophile, rapist, and traitor to coat my hands with his crimes”—language the Post read as a reference to Trump.

The writer reportedly said he planned to use buckshot rather than slugs to “minimize casualties” but would “go through most everyone here to get to the targets if it were absolutely necessary,” reasoning that guests who chose to attend were “complicit.” The document also mocks the Hilton hotel’s security: “I walk in with multiple weapons and not a single person there considers the possibility that I could be a threat.”

Within hours of the attack, Trump and a chorus of administration officials, GOP lawmakers, and right-wing influencers seized on the shooting to demand construction proceed unimpeded on a $400-million, 90,000-square-foot White House ballroom Trump is building on the demolished East Wing—a project mired in litigation from the National Trust for Historic Preservation, which argues he sidestepped Congress.

“This event would never have happened with the Militarily Top Secret Ballroom currently under construction at the White House,” Trump posted to Truth Social Sunday morning.

The White House Correspondents’ Association, which hosts the dinner, is not a White House organization—it is an independent nonprofit of journalists who cover the administration—and there’s no indication it would agree to hold the event, which is billed as a celebration of press freedom, inside the executive mansion.