OyZhana Williams went to University of Colorado Hospital on December 22, 2015 because her boyfriend had been shot.

Police were there to investigate the shooting.

Williams ended up being arrested, but not for the shooting.

Police accused her of assaulting a sergeant, scratching him across the head.

Williams says that’s not what happened; and her lawyers say surveillance video proves it.

They filed a lawsuit against three Aurora police officers on Monday.

The surveillance video was taken outside of the hospital’s emergency room. Lawyers say none of the officers involved was wearing a body camera.

Video shows police talking to Williams. She says the questioning from Sergeant Michael Hawkins became more aggressive, and he demanded the keys to her car.

Williams’ lawyers say that Hawkins had already searched the car and that he didn’t have the right to seize it, as he told Williams he was going to do.

Things got heated; when Williams refused to hand over the keys. She threw them on the ground. That's when she says Sergeant Hawkins tried to grab her.

The video shows Williams go into the back of a police car. Hawkins can then be seen grabbing Williams out of the back seat, standing her up and putting his forearm against her neck.

Williams is then thrown to the ground.

She says the same sergeant kicked her in the head while she was down.

Two other officers are named in the suit. Lawyers allege that Officer Jordan Odneal tackled Williams to the ground.Officer Jose Ortiz is also named in the lawsuit.

Lawyers say he wrote a sworn statement that featured false information. Attorneys say the affidavit stated that Williams first assaulted Sergeant Hawkins, scratching him on the head.

The affidavit was used to file charges against Williams, who spent several days in jail before posting bond.

Williams was prosecuted for second degree assault on a police officer. But nearly eleven months after the alleged assault, prosecutors dropped all charges against her.

Her lawyers say, had it not been for the surveillance video, Williams could have been found guilty and faced the mandatory sentence of four to 12 years in prison.

Lawyers say Williams was injured in the incident, suffering from pain, bruising, ringing in one of her ears and migraines.

The Aurora Police Department posted a message on Facebook regarding the incident.

Department officials say they were not aware of the excessive force allegations until the lawsuit was filed on Monday.

Williams, they say, did not file a complaint with the police department. Aurora’s police chief has ordered the Internal Affairs Bureau (IAB) to investigate immediately.

“We are taking this allegation seriously,” reads the posted statement, which also points out changes that have been made since the alleged incident.

Those changes include adjustments to the IAB, relocating the bureau off-site from police headquarters, adding investigators and reviewing policies and procedures.

The statement also noted that Sergeant Hawkins now works in an administrative role for the Aurora Police Department. Officer Odneal and Officer Ortiz are both still on patrol.

Williams is seeking monetary damages in the case.

Lawyers are requesting a jury trial.