You're looking at it the wrong way, serial killers who only target prostitutes are HEROES!
It's a good of the many kind of thing. A handful of dead prostitutes raises public awareness of the plight of the hapless street hooker and ire against their abusive Pimp Daddies. Eventually the people demand ACTION from the govmerment. A slick local politician will then hear the cry of the people and campaign on an anti-dead hooker platform. Then when he is elected and Bibles are distributed to 3 or 4 corner drug dealers, the people will forget about whatever it was that just happened and the local news will go back to reporting about cuddly kittens. Of course this calls for MOAR DEAD HOOKERS.
The work of a civic service minded serial killer is never done, and they never get the respect they deserve. And u guys should watch The Wire, it's like good n stuff.