CHICAGO -- A supervisor of the agency that investigates misconduct by Chicago police says in a lawsuit that he was falsely arrested and roughed up after an officer turned off his dashboard camera during a Jan. 1 traffic stop.

CBS Chicago reports that the video shows an officer arriving early in the morning on New Year's Day to the scene where George Roberts had been pulled over. The officer can be seen approaching with his gun drawn, and soon running back to his squad car to turn off the camera.

It is against policy in both Chicago and Illinois for a police officer to turn off his dashboard camera, CBS Chicago reports.

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Vehicles belonging to two other officers on the scene were equipped with audio recording devices, though no audio of the encounter was saved, according to the lawsuit.

Roberts said in the lawsuit, which was filed on Sept. 15, that the camera was shut off after officers realized he worked for the Independent Police Review Authority -- or IPRA -- the agency responsible for investigating police misconduct.

Roberts said he was initially stopped for a minor traffic violation, but was then pushed in the back by one of the officers and forced to the ground. He said in the lawsuit that an officer shouted, "Don't make me [expletive] shoot you."

But "when the (officers) turned off the dash camera, things got worse," his attorneys write in the lawsuit.

Roberts, who was handcuffed and placed in the back of a police vehicle, complained that the handcuffs were too tight, according to the lawsuit. The 6-foot-3, 315 pound man says that, instead, it would have have been appropriate for officers to use multiple handcuffs strung together for someone of his size.

He says in the lawsuit that one of the officers responded to his complaints: "What are you going to tell me next, you can't breathe?" -- an apparent reference to Eric Garner, a New York City man who died in 2014 as a result of a police choke hold.

Roberts also says he was told "that's your fault," when he pointed out that his weight made the single set of handcuffs painful.

When he complained more, he says he was removed from the car and shoved to the ground so forcefully that he lost control of his bowels.

The police complaint against Roberts -- who was later charged and found not guilty of driving under the influence -- noted that he soiled himself, but made no reference to video or audio recordings. The recordings were discovered by his defense team during the criminal trial.

Roberts says he was held in a lockup overnight, still wearing his soiled clothes. He notes in the lawsuit that he demanded to speak to the officers' supervisors, and that request was not granted, though a supervisor allegedly stopped by his cell, laughed at him, and walked away.

Roberts was initially suspended from his position with IPRA, according to the Chicago Tribune, but was allowed to return to work after he was acquitted earlier this year.

A police spokesman declined to comment, citing the pending litigation.