The gunman who attempted to assassinate former President Donald Trump during a campaign rally was considered a suspect by police before he climbed onto a roof and opened fire, the Pennsylvania State Police Commissioner testified Tuesday.

Pennsylvania State Police Colonel Christopher Paris told a hearing before the House Homeland Security Committee that 20-year-old Thomas Matthew Crooks was considered a suspect because he was “loitering” outside the rally in Butler, Pennsylvania, on July 13, but never attempted to enter.

Suspicions grew when Crooks was spotted with a rangefinder, a small binocular-like device used to measure the distance to a target, Paris said.

In the July 13 shooting, Trump suffered an ear injury, one protester was killed and two others were seriously injured before Crooks was shot and killed by Secret Service agents.

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