Great idea [[http://www.bbc.co.uk/news/uk-england-bradford-west-yorkshire-12201907 here]
In theory this seems like a good idea, I'm not sure how it would work in practice though. Prostitutes are at huge risk of all sorts of violent assault and murder, and I'll bet that the men who abuse prostitutes abuse other people in their lives too. This would make finding them and linking cases a lot quicker.