Thomas Crooks was perceived by the U.S. Secret Service as a "person of interest," not yet a "threat" after law enforcement saw him acting suspiciously and determined he had a golf range finder, according to Secret Service Spokesman Anthony Guglielmi.

Crooks was only identified as a threat when he "retrieved the weapon" and climbed onto the roof, according to Guglielmi, who adds that a threat requires, "a different protocol and a different course of action than a person of interest."

Guglielmi maintains that it was only once Crooks retrieved his weapon and got on the roof that he was identified as a threat.

Soon after that, Butler Township police officers confronted Crooks on the roof, and he pointed his weapon at one of them, who then dropped off the roof. Crooks then fired on former president Trump and was taken out by a Secret Service counter sniper.

This is a developing story and will be updated.