A stocky, forceful character player, Dennis Farina certainly looks like the popular idea of a cop with his weathered mug, ethnic air (Italian-American) and prominent, graying mustache. As well he should, this 18-year veteran of the Chicago police force was still a detective when he was introduced to producer-writer-director Michael Mann, a friend of a friend, who cast him in a supporting role in the dark, thoughtful crime drama "Thief" (1981). This successful performance led to work in Chicago regional theater (to which he has frequently returned in plays including "Streamers", "Heat" and "A