A veteran Chicago Police officer was convicted Friday of using excessive force in the beating of a South Side convenience store clerk.

Aldo Brown was found guilty of one count of one count of using excessive force and aqcuitted of two counts of filing a false police report.

A federal jury began deliberations Thursday and resumed Friday before reaching a verdict in the trial for the 38-year-old former officer. Brown was indicted in 2014 on federal civil rights and obstruction charges in connection with an incident that occurred in September 2012.

Brown reportedly testified in court that he and his partner were conducting an investigation into a tip that drugs were being sold at a convenience store in Chicago. Brown claimed that during the investigation he saw a handgun in the clerk’s pocket and ordered the man to put his hands up. Fearing for his life, Brown testified he tried to take down the man as the two grappled on the floor, the Tribune reported.

Federal prosecutors have claimed that Brown had no idea the victim had a handgun before the beating, arguing that it wasn’t until after the victim was in handcuffs that Brown knew about the gun.

Surveillance video shown in court reportedly showed Brown beating and kicking the man for nearly a minute before putting him in handcuffs and taking the gun away. He then allegedly kicked the victim again while he was handcuffed on the floor.

According to a 2014 indictment, Brown wrote in an arrest report, in part:

“P.O. Brown approached the above subject to conduct a field interview at which time the above subject stated to P.O. Brown, “I got some weed on me” and reached toward his rear pants pocket at which time P.O. Brown observed a handgun inside the above subject rear pants pocket. P.O. Brown conducted a emergency take down for officer safety and recovered the gun from the above subject rear pants pocket. The above subject was trying to pull away from P.O. Brown at which time P.O. Brown delivered a open hand stun to gain control of the above subject.”

But prosecutors claim that, according to the video, Brown’s account of when he saw the gun was 25 seconds before the victim reached into his pocket to grab a bag of weed.

Brown’s attorney reportedly argued in court that the store was in a violent neighborhood and a known drug spot and Brown had reason to be concerned for his safety. He said the video shows only one small part of what happened and alleged prosecutors don’t know for sure what Brown saw.

Still, prosecutors claimed that in a tactical response report filed after the incident, Brown listed the victim as an “active resister” who “fled” and “pulled away,” but did not report that he punched or kicked the victim.

The civil rights charge carries a maximum sentence of 10 years in prison. Brown's attorney says he plans to appeal the conviction.