Thomas Matthew Crooks Was Spotted 90 Minutes Before Shooting, Texts Reveal

Thomas Matthew Crooks was on the authorities' radar for a whole 90 minutes before he fired at Donald Trump, according to newly released text messages from law enforcement.

In the text exchange -- obtained by the New York Times -- one SWAT team member from PA's Beaver County Emergency Service Unit kicked things off at 4:26 PM ... writing to his colleagues, "Someone followed our lead and snuck in and parked by our cars just so you know."

The text continued ... "I'm just letting you know because you see me go out with my rifle and put it in my car so he knows you guys are up there sitting to the direct right on a picnic table about 50 yards from the exit." They were referring to Crooks, BTW.

Crooks was no longer at the picnic table -- but instead right below the counter-snipers by 5:10 PM. One of the counter-snipers took pictures of him and the photos were shared at 5:38 PM in the group chat.

They wrote this about seeing Crooks ... "Kid learning around building we are in. AGR I believe it is. I did see him with a range finder looking towards stage. FYI. If you wanna notify SS snipers to look out. I lost sight of him."

An officer added ... "Call it in to command and have a uniform check it out."

Of course, the authorities were incredibly slow to pounce on Crooks -- as we all know, he was able to fire off shots at DT, and grazed him on the ear. He was eventually killed by Secret Service around 6:11 PM.

SWAT members told ABC News Monday they were supposed to have a briefing when the Secret Service arrived -- but that never happened.

As we reported ... there were numerous security failures leading to the attempt on Trump’s life at his Butler, Pennsylvania rally.