Let's look at this considering the possibility that there is a mob connection. It still doesn't eliminate the possibility that each girl was targeted and/or stalked by a serial killer/client. Just because the women may have been associated with an "organized" group of pimps/drivers/bodyguards, etc does not mean that they and their ads weren't targeted by a client who is also a serial killer.
True, the woman and their drivers/pimps/bodyguards could have been recruited by the mob out of any of obvious sex trade jobs, even from their "independent" status or some may have gone independent or off the game plan (so to speak) without the blessing of the mob and then they were killed as a punishment but that doesn't necessarily preclude the killer taking some pleasure in torturing the women, calling the family members and then, out of some perverted sense of remorse or religious belief, laying them out in a ritual fashion.
True, the woman and their drivers/pimps/bodyguards could have been recruited by the mob out of any of obvious sex trade jobs, even from their "independent" status or some may have gone independent or off the game plan (so to speak) without the blessing of the mob and then they were killed as a punishment but that doesn't necessarily preclude the killer taking some pleasure in torturing the women, calling the family members and then, out of some perverted sense of remorse or religious belief, laying them out in a ritual fashion.