The shooting took place last week in suburban East Hazel Crest.
Chicago police were on surveillance in the suburb investigating a string of robberies.
They claim they shot Ryan Rogers, 27, when he drove his car at an officer's car.
According to police, when the detectives approached Ryan and his friend in a car and identified themselves, Ryan then rammed one of the officer's cars.
An officer fired and Ryan was hit and later died.
Rogers was laid to rest Friday in a private funeral in Harvey.
After the service, the attorney for Rogers family, Gregory Kulis, stood with relatives.
According to Kulis, witnesses tells a story different from the police's account, saying the officers never identified themselves and Ryan was trying to get away from the unknown man.
"Mr. Rogers then accelerated his vehicle and left the scene not knowing who the individuals were are what they were doing here," Kulis said.
A civil lawsuit filed by Roger's mother and the mother of Roger's two children alleges the officers use of deadly force was unprovoked.
The complaint claims wrongful death, battery and excessive force and seeks one million dollars for the alleged excessive force.
Mr. Rogers, who had no weapon, no contraband, was shot when he was driving down the street away from the officers
The chief of East Hazel Crest Police Department said Chicago police notified him about a robbery investigation but it's unclear if Chicago officers notified East Hazel Crest police the day of the shooting.
What is clear is that the family of Ryan Rogers is looking for more answers.