According to Fox News ... a group of U.S. Senators was briefed on the assassination plot Wednesday by FBI officials who told them before the attack on Trump, Crooks logged into the Steam platform where people go to play, discuss, create and purchase video games.

While communicating with other gamers, Crooks allegedly wrote, "July 13 will be my premiere, watch as it unfolds."

The senators were also informed FBI agents examined Crooks' laptop and discovered several searches with keywords such as "Trump," "Biden," "when is DNC convention," and "July 13 Trump rally."

However, law enforcement did not find any indication on the computer about why Crooks targeted Trump for murder.

Not just that ... but investigators have been unable so far to track down anyone who can point to Crooks' political leanings.

Furthermore, Fox reported the senators were advised that Crooks owned two mobile phones – and one was seized with a remote transmitter by police at the crime scene. Crooks' other phone – containing 27 contacts -- was found at his home. FBI agents are attempting to locate the contacts to interview them about Crooks.

What's more ... CNN is reporting Crooks had photos of both President Biden and Trump on his phone -- in addition to pics of Speaker Mike Johnson and House Minority Leader Hakeem Jeffries -- but there was no threatening language accompanying those photos.

As everyone knows, Crooks unleashed his diabolical scheme last Saturday, firing several shots from a building rooftop at Trump, who was giving a stump speech at a campaign rally in Butler, Pennsylvania.

Trump was grazed in the right ear while three spectators were also shot; one was killed and the other two survived. Crooks himself was shot and killed as a result.