The suspect accused of opening fire outside the White House correspondents' association dinner took selfies with weapons before the attack.
According to Sky News, the photos, which form part of a court filing by the US Department of Justice (DOJ), show Cole Allen dressed in black with a red tie.
Prosecutors say the images show Allen with a sheathed knife, a shoulder holster and what appears to be an ammunition-filled bag.
Allen took the photo of himself at about 8:03pm EDT on Saturday, about half an hour before he is accused of having rushed through the screening checkpoint with a raised shotgun.
The filing also claims that he tracked the president and first lady's movements via websites and live coverage from media companies of the event.
The filing states, “At some point before the attack, the defendant wrote emails explaining the actions he was about to take and scheduled those emails to be sent to specific people at approximately 8.30pm on 25 April - just minutes before the defendant, laden with weapons, sprinted through the screening checkpoint toward the dinner."
"Had the defendant achieved his intended outcome, he would have brought about one of the darkest days in American history," assistant US attorney Charles Jones wrote.
The DOJ also included photos of weapons, including a handgun and a shotgun, which they say were possessed by Allen when he was arrested.
The 31-year-old has been charged with one count of attempted assassination of the president, interstate transportation of a firearm and ammunition with intent to commit a felony and discharge of a firearm during a violent crime.
