Christopher Berry-Dee told the Sunday Tribune that he believes the killer is likely to "take a break" before embarking on another murderous spree. "He's had his Christmas present, he's had the grand-slam, he's gone completely berserk, " said Berry-Dee. "He's sitting back now and enjoying all the media attention. However, he will kill again, because these men always do . . . until they die themselves or are arrested. He will re-emerge, probably in a different area."

Berry-Dee, who has interviewed 30 serial killers around the world for his latest book, Talking With Serial Killers, has a long history in studying these type of murderers. He was also instrumental in solving a number of homicides in New York, when US serial killer Arthur Shawcross admitted to him that he was responsible for several killings.

Shawcross was known locally as 'the Monster of the Rivers', because he left his victims naked by the water. And the Suffolk Strangler also has a strong affinity with water, according to Berry-Dee.

"This is definitely not a town boy, " he said. "He's very comfortable in the country and around water. He may have been a fisherman." BerryDee believes the murderer is likely to be a "highly intelligent, highly organised white man between the ages of 30 and 40". This profile is slightly in conflict with earlier suggestions that the killer might be as young as 25. "I think he has to be older than that, because it takes time to develop the type of psychosis required to kill in this fashion, " he said.

"He will probably be working alone, and his preferred victim will be a white female between the ages of 18 and 30. He has almost certainly had problems with women in the past, maybe with a very domineering mother. He will be familiar with prostitutes, because he knows the line of chat . . . how to talk to get them in the car, even when they are wary."

The serial killer will have killed his victims within a very short time of them getting in the car, said the top criminologist. "The method of strangulation, whether it be manual or ligature, is significant. Shawcross told me that it takes up to eight minutes to kill a person through strangulation. It's not like the movies. It's very clinical and clean, but it's also incredibly painful for the victim."

As a result of the drawn-out killing process, Berry-Dee is convinced that the killer will be bearing defence wounds on his hands, arms, face and neck, and that he will be going to some lengths to hide these marks.

"It's something no one is talking about, and no one seems to have picked up on, " he said. "These prostitutes were feisty, street-wise women. They will have struggled and fought all the way with this man. They'll have been clawing at him, and at least one of the girls must have left some marks. I would be urging people to be aware of this, especially if anyone they know suddenly appears with a number of scratches that they can't explain.

"Either way, serial killers do not just emerge overnight. I cannot say for certain whether he has killed before, but he will most certainly be known to the police for previous crimes, possibly involving something like a sexual assault. The police already know this man."