He was 45 years old when he was shot 7 years ago. He was left with severe brain injuries.
Officer Airhart made improvements over the years, but there were also setbacks. Once close friend calls Airhart's death a relief because he no longer will have to suffer.
Services were held at the University of Chicago's Rockefeller Chapel. Hundreds of men and women dressed in police blue, Mayor Daley and other city officials paid tribute to Det. Airhart.
Detective Len Bajaenski called his former partner the best one a cop could have.
"The best, the strongest, the most dependable, the most loyal. Joe was everything, everything you could want. Deep down he was great person," said Det. Len Bajenski.
Det. Airhart died last Tuesday, 7 years after he was shot in the head during the arrest of suspected bank robber Salley in a South Loop apartment. The shooting left him unable to speak, walk or swallow food. Chicago Police Chaplin Father Thomas Nangle would often visit Airhart.
"Wasn't it amazing what the human eyes could do? And wasn't it amazing that he could squeeze our hands and squeeze our hearts… He knew he was never alone," said Father Thomas Nangle , Chicago Police Chaplin.
At the time of the shooting, Airhart worked on a joint police FBI task force with Chicago Police Supt. Jody Weis, who was then with the FBI.
"It's one of those guys that everybody wanted to work with. He had an infectious smile. Everybody loved him. He was a fun guy. He worked hard," said Supt. Jody Weis.
Airhart was remembered as a very loyal son, brother and father. His parents and other family members lined up with saluting police officers as the body of the 19-year veteran was carried out of the church.
"You think you prepare for this because you got seven years, but when the time comes it's still total shock. But I think Joe finally said it's time for me to go," said Bajenski.
Airhart grew up in Chicago's South Shore neighborhood. Many said he would return to his old neighborhood to help his parents a few times a week.
Salley was convicted of attempted murder a few years ago. He was sentenced to life. The state attorney will look into whether or not they will upgrade the charges to murder now that Airhart has died.