A trial gets underway in Cook County Court today for a suburban police officer caught on tape repeatedly striking a motorist with a baton.Streamwood police officer James Mandarino is due in court at 10 a.m. to face charges of aggravated battery and official misconduct.Mandarino’s own squad camera captured the images of the 41-year old officer repeatedly hitting 28-year-old Ronald Bell after a traffic stop.According to authorities, Mandarino confronted Bell and another man, Nolan Stalbaum, 38 of Glendale Heights, in Bell’s driveway after a traffic stop. According to lawsuit documents, Mandarino then allegedly shocked Stalbaum with a stun gun and ordered Bell to get on his hands and knees before beating him with a baton.Officer Mandarino has been on leave since shortly after the incident on March 28, 2010.A lawyer for the union representing Streamwood police says Mandarino denies wrongdoing in the alleged beating. Both Bell and Stalbaum have filed a federal suit against Mandarino.