Shooter had detonators in pocket for bombs in home, car, viewed Secret Service sniper through rangefinder moments before firing on Trump

CNN Chief Law Enforcement and Legal Analyst John Miller said that while there is still no motive or manifesto found of the shooter, authorities have developed "a lot of the background about what happened that day."

Crooks reportedly told his employer at a nursing home, where he worked as a dietary specialist, that he needed Saturday off because he had "something important to do." Crooks reportedly told his coworkers that he would see them on Sunday.

Crooks reportedly was placed on the radar of security when he went through the metal detector screening area with a rangefinder, which is used by shooters to measure distance. He did not have a weapon on him at the time, though he was flagged to keep an eye on. At some point, he left the secure area and didn’t pop up again until rally attendees were trying to bring attention to an armed person crawling on the nearby rooftop.

Around the time that Crooks was spotted by witnesses on the roof, a counter-sniper team spotted Crooks taking out the rangefinder and looking at counter-sniper positions, a senior law enforcement official told the outlet. "They were looking at him while he was looking at them," the official said. Crooks reportedly gained access to the rooftop by climbing on top of the building's air conditioning unit and pulling himself up.

After Crooks was neutralized following his attempted assassination of Trump, remote detonators were reportedly found on Crooks’ body that went to remote-controlled bombs found in Crooks’ car. An explosive device was also found at Crooks' residence. Sources said that Crooks was found with three loaded magazines and a bulletproof vest. "So it raises the question, did he expect to escape from this and if so, what was all that intended for," Miller asked.

Trump was struck in the ear by Crooks’ gunfire, and two attendees were injured. One man, father and former fire chief Corey Comperatore, was killed as he shielded his family from the gunfire.