Not 100% confirmed but from the same leaked info that brought us about the cash shop was also uncovered details about cop mode.
Apparently with cops and crooks, crooks get given criminal missions and teams of cops are assigned to stop them/catch them.
Cops have their own ranks and own locker system to collect different uniforms, as well as obviously access to police vehicles.
Police vehicles also have scanners to alert the player if the car they are targeting is stolen.
They are also assigned territory to patrol and gain bonuses from doing so.
Theres a few sources flopping around the net, as i say nothing is 100%, but it all sounds pretty awesome. It was dragged from the game files so no guarantee but hell, hope is a wonderful thing!