Thomas Matthew Crooks tested his shooting prowess at a western Pennsylvania gun range just weeks before last Saturday's attempted assassination of former President Trump, according to a report.

Bill Jenkins said he practiced his firearms skills immediately next to Crooks at the Keystone Shooting Center in Cranberry on June 22 – mere weeks before the July 13 attack, The Sun reported.

"I was sitting next to evil," Jenkins told the outlet. "I haven't been able to sleep thinking about it."

Jenkins, who said he has been interviewed by the FBI, recalled the class instructor extolling Trump during the session – a glorification that may have contributed to Crooks' determination to carry out the plot.

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Thomas Crooks. Keystone Shooting Center.

Thomas Matthew Crooks, 20, reportedly practiced at this shooting range before he opened fire at a Pennsylvania rally, injuring Donald Trump and killing a bystander. (AFP handout | Google maps)

"It turns out the instructor and I are Trump supporters," he said. "We talked about how our country was good under Trump. Our borders were secure, the economy was strong, we were energy independent, and he got things done. I noticed at the time that the kid wasn’t saying anything one way or another, but I could see him smirking."

In hindsight, Jenkins believes Crooks was muting his animus toward Trump – and that the conversation may well have helped to motivate his assault.

"It’s crossed my mind – did that conversation help push him over the edge?" he said. "It freaks me out a little because a person has died."

The 20-year-old, who had planned to pursue engineering in college, showed advanced skills on the shooting range, blowing holes in targets from significant distances, Jenkins told the newspaper.

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Donald Trump arrives to Trump Tower after being found guilty

Donald Trump arrives at Trump Tower, May 30, 2024 after being found guilty on 34 counts of falsifying business records in the first degree. (Felipe Ramales for Fox News Digital)

Crooks' shocking volley at the Trump rally grazed Trump in the ear, fatally struck rally goer Corey Comperatore, and injured two others.

Snipers cut him down soon after he launched his attack.

Jenkins, 62, an Air Force veteran, said he was stunned to learn that his training partner had nearly felled a former president.

"This guy killed a man with a wife and kids and almost plunged the country into chaos by killing Donald Trump," he said.

The pair's class lasted for several hours, with Crooks showing a clear familiarity and facility for firearms throughout, Jenkins noted.

"When we went to the range, he started shooting straight away," he said. "It seemed like he had experience with weapons."

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Thomas Crooks

Thomas Matthews Crooks opened fire on former President Trump at a rally in Pennsylvania on July 13, 2024. (Google maps | Handout | Wires)

Crooks brought his own 9mm handgun to class and dressed in a T-shirt and jeans, the outlet reported.

The long-haired gunman said little but was polite throughout, Jenkins recalled.

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After yet another accurate target strike, Jenkins lauded his younger counterpart.

"I congratulated him on how good he’d done, and he just laughed," Jenkins said.

Investigators have yet to reveal a motive for the assassination attempt and are continuing to comb through Crooks' background.