They also believe that if her clothes can be found, they could yield crucial DNA evidence in the hunt for a suspected serial killer who has terrorised Ipswich and provoked one of the biggest manhunts in Britain. The five bodies, all naked, were discovered in countryside over 10 days this month. All the women had been prostitutes to feed their heroin addiction.

Toxicologists are examining their bodies in the belief they may have been drugged before being strangled or suffocated, because there are no signs of struggle. Police said they were no longer looking for a murder weapon. Ms Alderton's body, which was found yesterday week ago, had been seen three days earlier but was mistaken for a mannequin. She was three months pregnant, but police said this was not relevant to the inquiry. Police are focusing their investigation on the prostitutes' clients.

They have spoken to the driver of a blue BMW that Ms Alderton was seen getting into on the night of her disappearance, and say they have not ruled him out of the investigation. Another man, supermarket worker Tom Stephens, 37, told The Sunday Mirror he had had sex with some of the women and believed he was a suspect because police had interviewed him four times. He said he had no alibis for the times at which the women were murdered, but denied all involvement.

He said he was particularly close to and a "protector" of Tania Nicol, 19, and Gemma Adams, 25 — "the best-looking girls who do this in Ipswich". The Mirror said police had confirmed Mr Stephens was a suspect. But the inquiry's head, Detective Chief Superintendent Stewart Gull, said: "Nobody has been spoken to as a suspect at this time." He said Suffolk Police had made contact with Interpol because they fear the killer may have fled Britain.

One theory is that the killer travelled through the nearby port of Felixstowe or is an itinerant who has now returned to mainland Europe. The 350 police on the case have received 9000 calls from the public and are trawling through 10,000 hours of CCTV footage. They are also examining lists of 400 known sex offenders in Suffolk and blacklists of violent clients drawn up by local prostitutes and massage parlours.

Mr Stephens said he turned to the prostitutes last year after his eight-year marriage ended because he was sad and lonely. "I made compromises on my morals to go down (to the red light district) the first time, so I suppose getting involved with them isn't a huge leap. "If you want to have a relationship with a working girl you have to accept the drugs. They work to do drugs as much as they breathe to live."

Ipswich is ringed by cars, commissioned from Merseyside police with automatic number plate recognition technology. They will log the plates of all vehicles entering or leaving the town and alert police if a car of interest is seen.

Assistant Chief Constable of Suffolk Jacqui Cheer likened the hunt to a jigsaw. "We have constructed the edges, now we have to fill in the middle," she said. The streets of Ipswich, a usually quiet market town, are all but deserted at night, despite the Christmas party season in full swing elsewhere in Britain. Many women refuse to go out alone after dark until the killer is caught. With AGENCIES