The Rachel Nickell case has drawn attention to profilers. The common perception of these relies on the TV series Cracker and another recent series Wire in the Blood. The slightly older will remember Silence of the Lambs. For the sake of the drama and story line, these profilers were presented as complex characters almost as out of synch as those they hunted.
I came across some research on American profilers which puts them in the status of stage hypnotists or mind-readers. They have a low success rate - in the mid-nineties, the British Home Office analysed a hundred and eighty-four crimes, to see how many times profiles led to the arrest of a criminal. The profile worked in five of those cases. That's just 2.7 per cent success. I do not know whether this was communicated to those who used profilers - I suspect not but they certainly gained higher credence amongst investigators than they deserved.