Darrin Hanna died a week after being arrested on a domestic battery charge.
His family says the tape is more evidence officers caused his death and after an emotional outburst at a North Chicago City Council meeting, Hanna's mother was led out of the room.
The coroner ruled Hanna's death was the result of a combination of drugs, trauma and poor health as well as the use of a stun gun by officers and prosecutors say police used reasonable force.
Hanna's family disputes those findings and the Lake County State's Attorney says there's not enough evidence officers crossed the line and has declined to file charges.
The family has not been deterred and they plan to file a federal lawsuit against the North Chicago Police Department and the officers involved.
Among the evidence is an audio recording of the confrontation.
The calm quiet of a city council meeting was shattered when a mother saw photos of her son in the minutes after a November confrontation with North Chicago Police.
Hanna's relatives also played for council members a police recording their attorneys obtained under a freedom of information act request.
"The story that's come out is that he was the aggressor and they were in fear of their lives which, when you listen to the this tape, Darrin Hanna is begging for his life and the officers are very calm and cool and collected," said Hanna family attorney Kevin O'Connor.
Police were responding to reports Hanna was beating is pregnant girlfriend. They insist his injuries were the direct result of his own belligerence.
The coroner's report concluded that multiple hits with a stun gun, plus physical trauma at the hands of officers contributed to Hanna's death as did pre-existing conditions including cocaine use and hypertension.
A state police review of the incident concluded the officers used reasonable force.
Monday night, North Chicago's mayor and interim police chief say this is the first they've heard that audio of the incident was caught on police radio.
"When the tape was brought to our attention, naturally you want to go back and talk to the officers and review the contents of that tape and we're in the process of doing that," said North Chicago interim police chief Jackson.
Hanna's family told the city council they've seen no urgency in the suburb's own investigation. "I need an answer about the police officers," said Hanna's mother, Gloria Carr. "What are you going to do? It's been over four months. I can't take this any long."
There were several minutes of police audio tapes given to Hanna's attorney.
It's not clear if that's the complete version of the tapes.
The six officers, meanwhile, remain on desk duty.
North Chicago's interim police chief promises their own internal investigation will be completed, and the officers' fates decided, next week.
