The parents of Donald Trump's would-be assassin Thomas Matthew Crooks called the cops to say he was missing before the shooting, a bombshell new report claims. 

It follows another stunning development that the 20-year-old gunman was at the former president's rally three hours before opening fire and sparked the suspicions of the Secret Service because he was carrying a rangefinder used by hunters to take long shots.

Crooks's parents called law enforcement in Bethel Park, Pennsylvania, to say they were concerned about their son's whereabouts, Fox News reported.