Experts profile murderer as white male, aged 25-40

Profiling could prove to be a vital weapon in the hunt for the Suffolk serial killer.

Detectives have been given a profiler, also known as a behavioural investigative analyst, from the National Centre for Policing Excellence at Bramshill Police College in Hampshire.

This "cracker" will help identify potential suspects. The process includes geographical profiling, in which a detailed analysis is drawn up of where the victims bodies were found, to help build a picture of the offender's "mental map" of the area. It can help indicate where the killer may work or live.

A detailed study of how the attacker committed the crimes will give an insight into his mindset. It could also show whether the killer is forensically aware or getting increasingly frantic.

The profiler will have learnt from previous serial killers, such as Peter Sutcliffe, the Yorkshire Ripper, who left his victims mutilated. In a similar way, each of the Suffolk victims was left naked. This might be because the serial killer wanted to humiliate them. It also means that by disposing of the clothing, he has robbed the police of a chance of gaining forensic evidence.

Michael Berry, senior lecturer in forensic psychology at Manchester Metropolitan University, said in an article describing the killer: "He will probably be between 25 and 40 ­ no one younger would have the maturity to kill five women. He will be white, because virtually no serial killers are black or Asian."

Colin Wilson, a criminologist, said "dumping [the bodies] in water" suggested the killer was "of above average intelligence". He said: "He knows that if the body floats for two days ­ as some of these have - physical evidence left will wash away.

"If the killer is not single his job requires him to work irregular hours or shifts so that he does not have unexplained absences, particularly at night when the girls go missing. It is unlikely to be a nine-to-five job.

"One possibility is that the killer is someone the girls felt comfortable with ­ a taxi driver, church worker, nurse or even a policeman. He is someone who does not raise suspicion by being in a red-light district."

David Wilson, a former convict, agreed that the attacker must be intelligent. "Killers who are disorganised are caught quite quickly, and our Suffolk killer has not struck me as being disorganised," he said. Joseph Diaz, associate professor of criminology at Fayetteville State University in North Carolina, said the attacks were sexually motivated, probably by impotence, and the killer was in his late 20s or early 30s.

"He has got the restraint of an older man in that he is able to keep driving around the area looking for a woman who is isolated," Dr Diaz said. "He seems to be losing control, like a drug addict, and is needing his 'fix' more often. He's growing ever-more confident."