LARGO — A white Largo police officer who appears to be choking a black teenager on video was fired Tuesday after an internal investigation found he violated department policy.Brian Livernois, 43, used undue force when he grabbed the 17-year-old boy around the neck in April, according to a summary of the internal inquiry by Largo police. The officer, who was hired by the agency in November 2012, also violated a policy pertaining to rude behavior and profane language."We take great pride in the positive relationship the Largo Police Department has with our community," Chief Jeffrey Undestad said in a statement. "Actions like this are not acceptable and violate the public's trust which every employee has worked so hard to earn."Livernois could not be reached for comment Wednesday. A representative with the Suncoast Police Benevolent Association declined to comment.The investigation summary gives this account:On April 4, Livernois responded to reports of a gun threat and battery after which the suspect was seen running down Melody Lane with several other people. PREVIOUS COVERAGE: Pinellas jail deputy fired, arrested after video shows him kicking inmate Officer Livernois found five people walking down the road, including the teen. He asked the teen, who matched the description of the suspect, if he had threatened to shoot someone. The teen laughed and turned away. The police department declined to identify the teen because of his age.The video footage begins at about this time. First posted on Facebook under the caption, “White Largo Cop Chokes Black Teen,” it was re-recorded on Youtube — the version cited in the investigation summary.It shows Livernois telling the teen to put out a Black and Mild cigar he was smoking. The two start to exchange words."You want to buck up on me, dude?" Livernois says, then, "You got a problem with me?""You got a problem with me?" the teen replies."Yeah, I do," the officer says.Livernois asks the teen to take his hands out of his pockets, and the two keep talking, although what they're saying is unclear. Then, Livernois says, "I'll f------ jack you up right now. Do you understand that?"The officer grabs the teen's right arm and walks him over to a police cruiser. The teen puts his arms up as Livernois says, "You want to f--- around with me?" A voice off camera can be heard saying to the teen, "Don't resist ... Don't resist." Livernois turns the teen so that his stomach is up against the hood of the cruiser. Then he grabs the teen around the neck, his right hand in back and left in front under his jaw.The people in the background start screaming. One man, wearing a red shirt, walks up to Livernois to try to pull him away. Livernois drops his hands from the teen's neck, about three seconds after he placed them there, and pushes the other man away.The officer then walks back over to the teen as the others are yelling, "Don't f------ touch him like that.""You're going to jail," Livernois says to the man in the red shirt.Then the video cuts off.PREVIOUS COVERAGE: Pinellas sheriff investigating deputies who hit suspect during arrestThe internal investigation began the next day when someone posted the video to the Largo Police Department Facebook page.An internal investigator reviewed Livernois' report from the incident. In it, he wrote that the teen "tensed up, postured in an aggressive manner by breathing heavy and pulled away from me," according to the summary. At his cruiser, Livernois wrote the teen "lifted his arms up in front of his body and turned his body facing me as it appeared he was going to fight me." The teen continued to resist, the officer wrote, so he put his "left hand underneath the black male subject's jaw to apply a quick contact pressure point with my left thumb to gain compliance," the summary says, and "placed my right hand behind the black male subject's head to try and calm the black male subject down."In an interview with investigators, the teen said he felt pressure on the back and front of his neck. He said it was hard to breath.Livernois told internal investigators that he originally confronted the teen because he had his fist balled up, and the cop was worried the teen would fight him. Livernois also said the teen had his hands tucked in the front of his shorts and that he was worried the teen had a gun, although he had not patted the teen down for weapons.The officer grabbed the teen's arm and walked him to the cruiser, Livernois said, "because if he did have a gun and I — you know, deadly force had to be used, I wanted it captured on video," according to the investigation. Some police cruisers are equipped with dashboard cameras.Livernois goes on to say that he applied pressure under the teen's jaw. He told investigators he was taught that the technique is normally used to pull up a suspect who is sitting down but that he thought it was okay in the encounter with the teen to "gain compliance and redirect the aggression." He denied grabbing the teen's throat or restricting his breathing. A sergeant who interviewed Livernois noted that the position of the officer’s hands deviated from the proper way of applying a pressure point under the jaw. "What you did in the video, do you remember that ever being taught in defensive tactics?" asked the sergeant, who was the instructor in Livernois' defensive tactics course."No," Livernois said.Along with the struggle with the teen, Livernois also arrested the man in the red shirt on an assault on a law enforcement officer charge and the teen on resisting arrest charges, said police spokesman Lt. Randall Chaney. Contact Kathryn Varn at firstname.lastname@example.org or (727) 893-8913. Follow @kathrynvarn.