By Dave Savini

(CBS) — A man is badly injured after a brawl at a popular River North restaurant.

The person throwing the punches: an off-duty Chicago police officer.

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CBS 2 Investigator Dave Savini has the videos and the story of the Clarke family.

“As soon as he hit him, the blood started to gush out of my husband,” Gail Clarke says, describing what happened inside Portillo’s.

Her husband, Terry Clarke, was repeatedly hit and suffered a gaping wound on his face. He was surprised to learn the man who punched him was a Chicago police officer.

“I didn’t know who he was,” said Terry Clarke.  “He didn’t act or seem like a police officer.  He did nothing to identify himself as a police officer.”

The Clarke family had just finished watching the Chicago Blackhawks win the 2015 Stanley Cup Championship before going to Portillo’s at Clark and Ontario.

“We were sitting here having a cheeseburger and got attacked,” Gail Clarke says.

Off-duty officer Khaled Shaar was moonlighting as a security guard at the restaurant. Near closing time, the Clarke’s say Shaar ordered them to leave mid-meal and called 9-1-1. But Shaar did not wait for police. Instead, Clarke says, Shaar attacked him and then arrested him.

“I was concerned for myself.  I was concerned for my family,” Terry Clarke, 61, says. “Because the guy was clearly irrational, overaggressive.”

The family has hired attorney Kevin O’Reilly, who on Wednesday filed a lawsuit against the offier, the restaurant and the private security company who hire Shaar.

“The off-duty officer pulled out a set off handcuffs, and put them around his knuckles like brass knuckles, and grabbed Mr. Clarke and punched him square in the face several times,” O’Reilly says.

“He landed some pretty good shots,” Clarke says. “You could see there is one haymaker that he missed, fortunately. Because if he had, I’d have brain damage.”

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The 2 Investigators found Shaar joined the force in 1999, and complaints against him started just months later. Chicago Police Department records show 23 complaints — five for excessive force and three for domestic violence.

CBS 2 found one 30-day suspension. Shaar even allegedly struck a man with a pistol in 2007 while off duty.

“He broke a man’s jaw over a road rage incident and was sued in federal court,” says O’Reilly, who noted that case quickly settled.

The Clarke family wants the cop fired and charged with felony assualt.

O’Reilly says Shaar’s report about this restaurant incident failed to match what is in the video.

“Shaar claims Terry Clarke picked up a chair and threw it at him and none of that is contained on the videotape,” the attorney says.

“You can still see it here on my eye,” Clarke said about the scar left behind. “We are going to see that justice gets done, and we are going to stick around until it does.”

Clarke was found guilty of disorderly conduct but was found innocent of felony battery.

Police say Shaar accused Clarke of throwing cheese at him. Clarke, an international business consultant, says Shaar used profanity and battered him with a deadly weapon. He wants Shaar charged with felony assault and removed from the force.

CPD officials say an investigation is being done by the Independent Police Review Authority.

“As a result of this incident, Officer Shaar was relieved of his police powers pending the outcome of IPRA’s investigation. The Chicago Police Department takes any allegation of misconduct seriously and continues to actively work toward greater accountability and public trust.”

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CBS 2 was unable to reach Shaar for comment