 Roy Scheider (qv) and Gene Hackman (qv) patrolled with  Eddie Egan (I) (qv) and Sonny Grosso (qv) for a month to get the  feel of the characters. Hackman became disgusted at the sights he  saw during this patrol. In one incident he had to help restrain a  suspect in the squad car and later worried that he would be sued for  impersonating a policeman.