Dr. John Horgan, psychologist, at an anti-terror conference:
"It will not work. It means different things to different people and there is the wrong assumption that if we can identify the traits of known terrorists we can move into predictions.-"Seeking out the suicide bombers." Paul Reynolds, BBC News.
"The terrorists are not a homogenous population and we simply do not understand why some move from legal activities to illegal.
"Too much is based on a limited range of people and we are seeing only the tip of the iceberg."
Despite Dr Horgan's comments, there was a good deal of profiling on display at this conference.
Peter Nessen of the Norwegian Defence Research Establishment had analysed the London suicide bombers and came up with a typology, which, he said, provided important lessons.
He identified four types of terrorist in the four young men who blew themselves and others up:
* the entrepreneur
* the protégé
* the misfit
* the drifter.