SEATTLE -- The Seattle Police Department confirms it has launched a criminal probe into an incident in which an off-duty police officer kicked an assault suspect in the head. And a witness says Officer Garth Haynes threatened several people with his gun before kicking the man who was lying on the ground under police watch. The incident that occurred outside the Balmar Bar and Lounge on Dec. 12 was captured on tape, which was exclusively obtained by KOMO News. The footage shows assault suspect Jake K. Clary was lying, face down, on the sidewalk with his hands cuffed behind his back. Haynes is seen moving toward the 21-year-old man and kicking his head, knocking his head into the sidewalk. One of the uniformed officers is then seen moving Haynes off to the side. According to the statement of probable cause, the situation began when Haynes, who was off-duty at the time, thought someone had stolen the jackets belonging to himself and his friend. Haynes told detectives he saw a woman standing outside the club holding the two missing jackets. Investigators said the officer then identified himself as police to the woman and told her to return the coats. The woman refused, and walked away, Haynes told investigators. The officer called 911 and started following the woman. And that's when he says three men attacked him and his companion. But according to a witness, the situation began inside the nightclub where Haynes and his friend tried to chat up the group of women she was with. "They were a little too tipsy. They both had a little too much to drink, because they're being a little too touchy-feely with some of the girls," she said. The women decided to leave when the bar became too crowded, the witness said, and gathered their jackets. "I asked my sister (to) grab my jacket, reach across the table and grab all the coats off our table. Because it was our table - it was reserved - and all the stuff is ours, you know," she said. While the women were smoking outside, Haynes came charging at one of them, the witness said. "My sister was approached by this gentleman, and he said, 'You have my jacket,'" the woman said. "My sister was like, 'Oh, sorry ... Some of my friends were still in the bathroom ... I thought it was their (my friends') jacket, I apologize. Here's your jacket." But that wasn't the end of the situation, said the witness, as the man came back and accused her sister of stealing his jacket. He wouldn't let up even when she explained she'd made an honest mistake, she said. "He was like, 'Nope, you stole my jacket. You stole my jacket. I'm a police officer. I'm arresting you,"' the witness said. "And we all look at him - including his buddy, the guy that was with him - and we're all like, 'Dude, just let it go. It's not a big deal.' "You can tell at that point that he's belligerently drunk because he reeked of alcohol, and he was talking like he was belligerent drunk." The situation intensified when the man grabbed her sister's arm and began pulling her, the witness said. When several of their male friends interfered, the witness said the man pulled out a police badge and a gun. "And then the guy grabs his badge, opens his shirt, shows his badge and unbuckles the thing for his gun. Then (he) puts his hand on his gun and pulls it out, and puts it back in," she said. "And this guy's grabbing onto my sister. My sister had a bruise on her arm the next day. This guy was holding onto her for his dear life." The struggle had migrated to the middle of an intersection when three men appeared out of nowhere, the witness said. "(They) start telling the cop to let her go, let her go," she said. "He wasn't having it. All of a sudden all hell breaks loose. It's pouring rain out. Before I know it, I look behind me and these guys and the officer are fighting. And it was a full-on brawl." According to the statement, two of the men attacked Haynes, punching and kicking him, while the third attacked the officer's friend. The three men claim they only attacked because they thought the woman needed help. "They saw somebody they thought was in trouble. They attempted to help or intervene," said Clary's attorney, Tim Leary. But it's what happened after on-duty officers arrived and subdued the situation that landed Haynes at the center of a criminal investigation. "Jake was doing what he was supposed to be doing, which was complying once uniformed officers arrived following their commands," said Leary. "(The) officer came up, and the video speaks for itself." In a written statement, Seattle police said, "As the investigation commenced, the off-duty officer made physical contact with one of the three handcuffed subjects. The investigating officers prevented any further contact between the off-duty officer and his assailants." The three assault suspects - Clary, Jason R. Lamb and Simon L. Thayer - were booked into the King County Jail, and have since been charged with third-degree assault. Haynes was treated at the scene, then taken to an area hospital for additional treatment. Seattle police said the investigating officers immediately reported the off-duty officer's actions to their supervisor. Haynes, who was hired by the department in January 2009, was administratively reassigned on Dec.14. But the attack was not immediately made public, according to Leary. "The police reports made absolutely no mention of this assault, which, frankly, is what it is -- an assault by the officer against Jake," he said. The kicking incident is another questionable episode for a department already under a cloud of allegations about misuse of force, including last year's fatal shooting of Native American woodcarver John T. Williams, the punching of a woman during a scuffle after a jaywalking stop, and the stomping of a suspect detained by Seattle police last spring. Citing an apparent "erosion of trust" between police and the public, the Department of Justice has launched a review of the police department.