Trump's attempted assassin posted message before shooting: 'July 13 will be my premiere, watch as it unfolds'

Thomas Matthew Crooks apparently teased an attack online days before he climbed onto a roof and opened fire at a Pennsylvania campaign rally, killing one and injuring others, including former President Donald Trump, Fox News has learned.

Secret Service and FBI officials told U.S. senators during an all-members briefing on Wednesday, July 17, that Crooks, 20, wrote a threatening message on the gaming platform "Steam" days before the attempted assassination in Butler, Pennsylvania, on July 13, Fox News’ Jacqui Heinrich reported.

According to the officials, Crooks allegedly wrote: "July 13 will be my premiere, watch as it unfolds."

"Steam" is a popular platform where tens of millions of gamers purchase games and communicate. The discovery was made as investigators continue to review Crooks’ technological devices, including his cell phones and laptop.

SECRET SERVICE CONTINUES TO FACE QUESTIONS AS FBI INVESTIGATES TRUMP SHOOTER THOMAS MATTHEW CROOKS

When investigators reviewed the laptop, they found a few searches in July of: Trump, Biden, when is the DNC convention, and the July 13 Trump rally, America’s top security officials told the senators on Wednesday.

The investigators found no evidence of a particular ideology on the laptop, which the FBI believes is notable, and nobody in interviews reported Crooks discussing politics, according to senators who spoke with Fox News after the meeting.

The senators also learned that the suspect had two cell phones. The primary phone was recovered from the scene along with a remote transmitter.

TRUMP SHOOTER'S PARENTS CALLED POLICE HOURS BEFORE ASSASSINATION ATTEMPT

A second cell phone found at the home had only 27 contacts. The FBI is in the process of tracking down and interviewing those people, they told the senators.

The development comes just hours after it was learned Crooks' parents contacted law enforcement on Saturday hours before the attempted assassination.

The would-be assassin's mother and father told local police that Crooks was missing and that they were concerned about his welfare, a source told Fox News.

It remained unclear if they knew that he was in possession of an AR-15 rifle that belonged to his father.

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Police have not said what actions they took after they were contacted.

Fox News’ Rebecca Rosenberg, Jake Gibson and David Spunt contributed to this report.