On September 12, Mendoza was driving the Number 62 bus when he said off-duty Officer Thomas O'Grady attacked him. The officer, who was on a bike, claimed Mendoza cut him off in traffic.
Prosecutors say witnesses aboard the bus report there was yelling between the two men but no physical contact. The incident was recorded on surveillance tape.
Mendoza filed a federal lawsuit against O'Grady and the City of Chicago.