Photos included in the memorandum showed Allen posing in front of a mirror with several weapons strapped to his body, including a sheathed knife, and a bag with ammunition.
They alleged that during the following half hour, Allen checked several websites for live coverage of the White House Correspondents’ dinner.
He then made his way downstairs and towards the ballroom, where the event was taking place.
Prosecutors said he sprinted through a metal detector, holding a shotgun with both hands in a raised position.
