A local officer acting as a sniper at Donald Trump’s Pennsylvania rally on Saturday spotted Thomas Matthew Crooks and took a picture of him in the minutes before he fired on the former president and his audience, a law enforcement source with direct knowledge told CBS News on Tuesday. The sniper was a member of a three-man counter-sniper team stationed inside the building where an unchallenged Crooks clambered onto the roof and set up to shoot at Trump. From his position inside the building, scanning the crowd, one of the snipers witnessed Crooks outside, looking up at the roof, before he disappeared, CBS’ source said. Crooks then reappeared, sat down, and took out his phone. At that point, CBS reported, one of the snipers took a picture of Crooks, who then looked through a rangefinder, a tool similar to a pair of binoculars that is used to measure distances when setting up long-range shots. The sniper tried to radio to the command post and send the photo he’d taken up the chain of command, according to CBS. It is unclear if the command received the sniper’s calls, and Crooks scaled to the roof soon after.