KNOXVILLE, Tenn. (WATE) — Law enforcement officers in Knoxville are sharing what they look for when they’re investigating illegal gun sales.

ATF agents included pictures in court documents that allegedly show Michael Harris shopping at a Knoxville gun show. He was arrested after a chase and crash that sent a Knoxville police sergeant to the hospital.

The documents also show that agents have put gun shows under scrutiny for at least a year. They use undercover officers and look for specific signs that could potentially lead them to people breaking the laws on selling guns.

While Knoxville Police couldn’t talk about the specifics of Harris’ case, they could describe activities that catch their eye.

“If individuals come in and they’re obviously on the phone with some type of live streaming where they’re showing the merchandise to someone not on scene, that’s obviously indicative of them purchasing on behalf of someone else,” Lt. Joshua Shaffer at the Knoxville Police Department said.

Gun shows in Knoxville have been under scrutiny before. In 2019, the city council passed a resolution banning them on city-owned property.

“There are people that try to take advantage and exploit the right of a private seller to sell a firearm on their own,” Shaffer said.

It’s why Shaffer asks buyers and sellers to stay cautious, ask questions, and if you see something unusual – say something.

“If you sold a car, I’m sure you would write down who you sold it to, in case the person gets a red light ticket the next week and it doesn’t fall back on you. We ask the same thing with a gun. Just record who you sold it to, make sure they’ve got ID, just ask a few questions and make sure that they’re not a prohibited person, and that they’re a lawful gun owner, and that can make all the difference in the world,” he said.