Darrin Hanna's family says the recording helps prove police caused his death.
The interim police chief in North Chicago says it is an ongoing investigation. But Hanna's family says they are filing a federal lawsuit in light of the new audio tape.
Lake County's state's attorney says there's not enough evidence that officers crossed the line, and did not file charges.
North Chicago's interim police chief says the department's internal investigation should be done next week.
Hanna's mother broke down after seeing photos of her son following a November confrontation with North Chicago police. It happened after Hanna was detained for allegedly beating his pregnant girlfriend. At the city council meeting Monday night, relatives also played a police radio recording of the altercation.
North Chicago's mayor and the interim police chief say it is the first time they heard the police radio recording.
"When the tape was brought to our attention, naturally you want to talk to the officers in regards to the contents of that tape. We're doing that now," said James Jackson, North Chicago's interim police chief.
Hanna died a week after the incident with police. The coroner concluded the cause was multiple stun gun hits, physical trauma at the hands of officers and preexisting conditions, including cocaine use and hypertension. Hanna's family says the tape is more evidence that officers caused his death, and they're demanding officials take action against the officers.
"I need an answer from you and I need an answer immediately," said Hanna's mother, Gloria Carr. "About the police officers, what are you going to do? It has been over four months."