A fired Pittsburgh police sergeant was convicted Friday of violating the civil rights of drunken teenager he beat at a high school football game. Stephen Matakovich, 48, twice pushed and then punched Gabriel Despres, then 19. The confrontation took place just outside Heinz Field, home of the Pittsburgh Steelers, during a high school championship football game on Nov. 28, 2015. Stadium security guards had called Matakovich to forcibly remove Despres, who was drunk and had been denied entry. Matakovich "was an annoyed bully who beat the crap out of a drunk kid," Assistant U.S. Attorney Stephen Gilson told jurors on Friday. "This was an officer abusing his power." The jury acquitted Matakovich of a second charge, falsification of a document. Federal prosecutors contended Matakovich lied about or exaggerated Despres' actions in the reports he filed to justify pushing and hitting him. The Steelers, who run the stadium, sent surveillance video of the altercation to then-police Chief Cameron McLay early last year. Mclay then fired Matakovich and ordered the investigation that resulted in related state criminal charges and, eventually, federal charges. The federal civil rights charge carries up to 10 years in prison. Sentencing was scheduled for Sept. 15. Raw Video: Violent arrest caught on Heinz Field cameras Matakovich, who testified in his own defense, said Despres' movements were "subtle" and "surreptitious." A retired state police instructor testified for the defense that Matakovich was reasonable in his use of force, because he noticed things about Despres' posture and demeanor that the other witnesses -- and the jury -- weren't trained to observe. Lead defense attorney Tina Miller, a former federal prosecutor, told the jury that dissecting the 29-second encounter in a one-week trial was unfair to Matakovich, who could be trusted for the "split-second" judgment he made. "Nobody is going to say to a police officer, 'I'm going to assault you,'" Miller told the jury. "You're not going to advertise what you're going to do. Your actions are going to be subtle. It's not going to be like some poster or (TV commercial)." She defended Matakovich as "one of those guys on that thin blue line between chaos and order" before asking the jury, "Do we really want to second-guess?" But Gilson mocked the defense, asking the jury if they really needed special training to tell the difference between an open hand and a closed fist. "The only way (Matakovich) can convince you that what he did was reasonable is to convince you that you can't trust your own eyes," Gilson said. The video appeared to contradict several of Matakovich's claims, and prosecution witnesses -- including five security guards -- who testified they never saw Despres adopt a fighting posture, clench his fist or stare menacingly at Matakovich. The fired sergeant also faces a state court trial next month on charges including simple assault, official oppression and perjury stemming from his testimony at an earlier court hearing. Despres has since pleaded guilty to citations for public drunkenness and defiant trespass. He was ordered to pay more than $900 in fines and court costs, although more serious charges that he assaulted Matakovich were dropped.