Chilling message left by Trump gunman before assassination attempt

The 20-year-old was shot dead at the scene of the assassination attempt.

Crooks was shot dead by Secret Service agents after firing several shots in the direction of former President Donald Trump at a Republican rally in Butler, Pennsylvania last Saturday.

A bullet shot from Crooks' AR-pattern rifle clipped the ear of the 78-year-old. That same bullet is the one believed to have killed 50-year-old volunteer fire chief Corey Comperatore.

Two others were seriously injured.

According to multiple law enforcement sources, investigators found a post on the gaming platform Steam that is credited to the suspected gunman.

The post reads "July 13 will be my premiere, watch as it unfolds." Investigators are working to determine whether the post is legitimate.

Internet searches for both Trump and President Joe Biden were also found on the phone belonging to Crooks.

Investigators told ABC7 News that Crooks had searched for the dates of Trump's rally in Butler, Pennsylvania, and for those of the Democratic National Convention in Chicago.

Crooks had been registered as a Republican voter, according to state records. But a $15 donation to a progressive group was also recorded under "Thomas Crooks" in January 2021, according to FEC records.

On Sunday, the FBI released the name of Crooks as the suspected gunman behind the attack.

The statement read: "The FBI has identified Thomas Matthew Crooks, 20, of Bethel Park, Pennsylvania, as the subject involved in the assassination attempt of former President Donald Trump on 13 July, in Butler, Pennsylvania."

"This remains an active and ongoing investigation."

Witnesses told the BBC they saw a man with a rifle crawl onto a roof while Trump was speaking.

“We noticed a guy crawling… up the roof of the building beside us, 50 ft away from us,” they told the outlet.