i like this idea.
Watching them get fully arrest as you say, and then following the squad car or paddywagon (if a group is arrested) to the jail to break them out... or kill them as part of a mission or contract. Is miss the actual police chases from San Andreas. I would follow them and try to crash the car so they would get out and have a gun battle on foot. All the while I'm sitting back taking pictures of it. The cops always won, too.