Terry Clarke, a 61-year-old Canadian businessman, was with his family in 2015 eating at the restaurant when he got into a physical altercation with Kalhed Shaar.
Several videos from every angle inside the restaurant, as well as patron cellphone video, conflicts with what Shaar told police about the incident.
Clarke, who has a scar from the altercation, accuses Shaar of using excessive force and others for covering it up. He says his life has changed forever.
After the incident, Clarke spent 48 hours in the Cook County Jail. Eventually, he was found not guilty on felony battery charges against a police officer. Meanwhile, Shaar has been relieved of his police powers pending the outcome of an investigation by the Independent Police Review Authority.
"He needs to be prosecuted, he is unfit to be a police officer and he is menace to other police officers who have to cover up for him," Clarke said Wednesday after filing a civil suit against Shaar.
Despite videotape evidence and witness accounts, a year and half later, IPRA is still investigating.
"We're only a handful of people at this point, we're not only trying to keep IPRA running, and also build a new agency at the same time," said Sharon Fairley, IPRA Chief Administrator.
Fairley said because IPRA is understaffed and in the process of becoming a new police review agency, it's not possible to investigate all cases in a timely manner.
As for criminal action against Shaar, the Cook County State's Attorney's officer only received the case from IPRA six months ago. Current policy states that decisions about criminal charges against police officers must wait until IPRA completes its investigation.
"It becomes a vicious circle if the SA office just sits on it or buries and nothing happens that is a problem with the system," said O'Reilly.
Clarke, his wife and their son stopped in Portillo's for a burger following a June 2015 Stanley Cup Blackhawks game. During closing time, while several other patrons were still in the restaurant, Clarke said Shaar singled them out and demanded that they leave.
"His attitude towards us was overly aggressive, which seemed strange to me because we were just like everybody else sticking around finishing a burger," Clarke said.
Clarke said Shaar then grabbed his food out of his hand. After, words were exchanged. Clarke said Sharr took his handcuffs and used them as brass knuckles and punched Clarke several times.
Clarke's wife Gail said she tried to intervene.
"The blood started to pour out of Terry's face and I just thought, 'I have to get up there.' It was like, 'Stop, just stop hitting him,'" Gail Clarke said.
The Clarke's didn't know Shaar was a police officer because he was wearing shorts, a T-shirt and gym shoes. Terry Clarke said not until he was in handcuffs, arrested for felony battery, did Shaar indicate that he was a cop.
Shaar told police that Clarke threw a chair at him and punched him, which is never seen on the videotape.
"It's very annoying that the wheels of justice worked quickly to charge Mr. Clarke with felonies but when it comes to changing the actual perpetrator, it's been a year and a half and nothing has taken place, it's been disturbing," said Kevin O'Reilly, Terry Clarke's attorney.
The felony charges were eventually dropped against Clarke.
Newly elected Cook County State's Attorney Kim Foxx has promised to change the system, she's proposing to no longer wait until IPRA acts to charge a police officer. Foxx want's her team to run parallel investigations with IPRA to move police-involved cases along.