silent dust
Apparently there are potential plans to have cops make arrests with explosive helmets and concerns that this would make slavemasters redundant. If this is done then my simple suggestion would be to just link the two as opposite ends of the same "justice" system, the cops fit people with explosives while making the arrest and then if the criminal can't afford the extremely high fines once they get back to the station they will be entered into actual slavery and shipped off to licensed slavemasters for resale. This also allows you to keep the existing slave purchasing mechanics without needing to find some weird way to add to the cop behaviors, maintaining both lore and mechanical distinctions.
As a bonus suggestion this could even be implemented as a penalty for the player getting arrested (assuming that becomes an option), resetting you to the nearest police station where you will either lose a ton of money paying bail or actually become enslaved to someone yourself which would probably work similarly to the bouncer's bodyguard mechanics but reversed to where your owner does the leading and you'll explode if you don't stick within a certain distance (probably larger than SoR1 slaves so you have more options to work out an escape plan, but still small enough to be painfully limiting). All of that is a bit more ambitious though, the main idea is just finding a good reason to keep slavemasters around in the setting.
Prisons could exist as a mid-point holding area between the station and slave shop or are maybe where they just dump people who are deemed too dangerous to enslave.
elfin sigil
silk dome
mellow bronze
weak nexus