An officer from a tiny police department in south St. Louis County is caught by an undercover camera cussing out a young driver, and threatening to throw him in jail.

"You wanna try me? You want to try me?"

"You think you've had a bad night? I'm gonna ruin your [expletive] night."

"Do you want to try me? Do you want to try me young boy?"

The 'young boy' is 20 year old Brett Darrow, a south St. Louis City resident.

"I was scared," Darrow says of his experience early Friday morning in a commuter parking lot in St. George. "I was honestly scared."

It was 2AM Friday. Darrow says he was pulling into the lot to meet a friend. But an officer followed him in, claiming he looked suspicious. The officer asked him to show his ID, and when Darrow questioned why he was being stopped, the officer eventually told him to get out, then he cussed him out. But when Brett's car is running, a tape is too.

"Do you want to try me tonight young boy?" the officer yells, over and over. "Do you want to go to jail for some [expletive] reason I come up with?"

"I think the officer should be fired," Darrow says. "It was unexcusable, not a minor slip up."

Darrow put his camera in his car about a year and a half ago, he says, when he got a traffic ticket he thought he didn't deserve.

"There was no way to really fight it, no way to prove I was right. I thought then, what better way to prove it than to have video evidence," Darrow says. "It comes on with the car, it shuts off with the car. It's on all the time when I drive."

The officer has belonged to the St. George police force for two years.

"I saw that and I was like, no, that didn't just happen," Chief Scott Uhrig says, describing his feeling when he saw the video of his officer that has been posted online.

"Our officers aren't trained and taught to treat citizens that way theyr'e trained to be curteous and respectful no matter what the circumstances are."

Uhrig put his officer on unpaid leave and says the investigation is now underway, and will include a close look at the video from the officer's own cruiser cam. While the chief questions the sergeant's moves, he also questions Darrow's motives.

"Most people commuting back and forth to work don't keep their car outfitted with video recording devices and audio devices," Uhrig says.

Uhrig says he wonders if Darrow is setting up police officers.

"I'm not setting them up," Darrow says.

But this isn't his first run in to be taped. He also posted online video an altercation with St. Louis County Police during a DUI checkpoint. But police say he never filed a formal complaint through internal affairs. That's why some question whether he's a victim, or a vigilante.

"They have cameras in their cars," Darrow says of police. "Why can't it be the other way around?"