The detectives leading the investigation into the Ipswich murders yesterday warned other towns and cities to be on their guard against the serial killer amid fears he may now come to Norwich.

The detectives leading the investigation into the Ipswich murders yesterday warned other towns and cities to be on their guard against the serial killer amid fears he may now come to Norwich.

The most senior investigating officer told the EDP that she had given specific warnings to police in Norfolk and Essex to be particularly wary.

And a series of behaviour experts said that whoever was responsible for the death of five prostitutes is likely to keep on killing - though not necessarily in Ipswich.

Despite seeming to have taken at least one of the murdered prostitutes, Paula Clennell, from under the eyes of Suffolk police last weekend, the killer does not appear to have made any further abduction attempts since then.

No prostitutes have been reported missing since Monday and no bodies have been found since Tuesday, with police now concentrating their efforts on analysing CCTV footage and gathering forensic evidence from stray clothing.

With 350 police officers and support staff brought in to Ipswich to find the killer - and a media circus descending on to the town's red light district every night - the likelihood of another murder taking place there seems remote.

But professor of forensic psychology Mike Berry, who has been studying the case, said: “Despite all the media and police attention the murderer has not lost the urge to kill and will carry on, though not necessarily in Ipswich.

“The killer may cool off for a while but all he needs to do is move to a new city to confuse the police. If he did switch hunting grounds the cooling-off period would not last long.

“His passion for killing will last for a while yet and he could kill anywhere in the country.”

Speaking to the EDP yesterday Suffolk's Assistant Chief Constable Jacqui Cheer said that the likelihood of the killer now striking elsewhere was a very real possibility.

She said: “I've already spoken with my ACPO (Association of Chief Police Officers) colleagues in neighbouring forces about their need to step up work in red light areas and offer general advice to women about staying safe.

“It is possible the killer or killers might move on and we are taking advice about that. It might be that he stops targeting working women.

“I receive new information about risk assessment every morning and it's my responsibility to cover all these potentials.”

Last week Norfolk police Chief Constable Carole Howlett said: “We've increased patrols in our red light district and are liaising with people who support sex workers.

“We would advise sex workers not to go out alone because they are at significant risk at the moment.”

This weekend Det Chief Supt Stewart Gull, who is spearheading the hunt for the killer, said that he would not speculate on whether those responsible might now strike elsewhere.

But, aware of possible links between the latest killings and those in Norwich between 2000 and 2002, he said that detectives may well go back to study those earlier murders in the future.

Mr Gull said it was important that police forces, including Norfolk, remained alert to the potential of the serial killer moving to other locations.

He said: “The idea that the killer or killers may now go somewhere else to murder is speculation and my priority is to find the persons responsible rather than to speculate.

“But our colleagues in other forces around the country are aware of the possibility and I know in many areas, including Norfolk, they're building in their own preventative measures.

“There is that risk there, of course, but I can't say more than that.”

Mr Gull thanked Norfolk police who he said had been “particularly helpful” this week, sending the first batch of detectives from outside forces to join the investigation, along with other officers and support staff including divers and press officers.

He emphasised that working girls might “hold the key” to cracking this case and said that Suffolk police were doing all they can to prevent any more prostitutes falling victim to the killer.

He said: “We have undertaken significant preventative work and we're looking to minimise the risk to any other working girls in this area.

“There has been a clear message this week that it's not safe for prostitutes to solicit in any form, both on the street and off the street. Those who continue to do so will be at risk until the persons responsible for these murders are detained.

“I can't second guess what the individuals are going to do, all I can say is that my goal is to detain them as soon as possible.”

Mr Gull also said he was keeping “an open mind” as to whether the killer was local or from further afield.