Snipers Took Photos of Thomas Matthew Crooks Before Trump Shooting, Aftermath on Body Cam

Shocking new body cam footage shows Thomas Michael Crooks lying dead with a stream of blood leaking out of his head on the rooftop of the Pennsylvania building where he tried to assassinate Donald Trump.

U.S. Senator Chuck Grassley (R-IA) released the footage capturing Secret Service agents chatting with law enforcement officers in military gear as they stood on the roof around Crooks' corpse minutes after the 20-year-old was shot to death by a sniper.

As you know, Crooks fired shots at Trump with AR-15-style rifle while the Republican presidential nominee was giving a stump speech in Butler, PA. Trump was grazed in his right ear while 3 spectators were also shot -- one fatally.

At one point in the video clip, the SS agent is told a sniper snapped photos of Crooks and sent them around to law enforcement during the rally.

The new footage also shows the trail of blood coming from Crooks' corpse ... and his AR-15-style rifle is also visible on the rooftop.

It sounds like the sniper who took the pics of Crooks ultimately lost him ... and the guy slipped past security and got on the roof for the assassination attempt.

As we reported ... Secret Service director Kimberly Cheatle resigned Tuesday after being grilled on Capitol Hill over security failures at the Trump rally, which left one man dead.