Trouble is Lambsy in these type of crimes you have to have the co-operation of the victim & they very often don't carry it through, which I think is why the police are reluctant to interfere, & then as ive said before it very often ends in a death.
How can you prevent a crime if you don't know what's going on, these guys present themselves to others as a nice guy, how often do you hear , " what! But he was such a great fellow, I don't believe it!!."