By Chris Summers
BBC News, Ipswich
Police in Suffolk say the death of a fourth woman is being treated as murder after a pathologist confirmed she had been strangled.
Thousands of people have contacted police over the murders
A post-mortem examination on the fifth victim is expected later. Where does that leave the murder inquiry?
Momentum is vital to any police inquiry and there can be no doubt the hunt for the "Suffolk Strangler" has considerable momentum at present.
Suffolk Police's special hotline has received 5,500 calls since it was set up, the incident room has received 1,000 e-mails from the public and hundreds of people have contacted the police in person.
But the danger when this sort of inquiry reaches such a scale is of detectives drowning in a sea of information.
That is what happened with the Yorkshire Ripper case.
Cliff Dixon, a former deputy chief constable with Bedfordshire police, told the BBC News website: "You are getting to the stage where the information is escalating.
"Every phone call coming into the incident room results in an action and for every action you might have two or three actions coming out of it.
"For example if someone says go and speak to the owner of the corner shop, you may go and see him and his information may lead you in two or three different directions."
Mr Dixon said: "What happened with the Yorkshire Ripper is that their cross referencing fell down."
Det Ch Supt Stewart Gull faces a number of red herrings
That meant that, although Peter Sutcliffe was in the system several times, detectives were unable to notice his importance.
Now the police work with a sophisticated computer system called HOLMES but Mr Dixon said: "HOLMES doesn't prioritise things for you. That is still up to the senior investigation officer and his management team."
Another problem facing Det Ch Supt Stewart Gull and his team is the danger of red herrings.
The classic example of that was Wearside Jack, the hoaxer whose tapes and letters completely sidetracked the Ripper squad.
Mr Dixon said: "It's indicative of the way in which, if you're not careful, you can be pushed in the wrong direction and the media can fuel that."
Thursday's papers were full of suggestions for possible "breakthroughs" which could easily be red herrings.
A fat man in a BMW supposedly seen picking Anneli Alderton up last Thursday.
A suggestion the killer had contacted the victims by phone and may even have sent a text message from Anneli's phone after killing her.
The discovery of clothes in a river.
A possible link with the 1992 murder of Norwich prostitute Natalie Pearman.
A suggestion the killer might be a lorry driver, an immigrant worker or a member of the RAF or US Air Force.
The claim that the killer shaved all his victims.
The idea that the killer's "calling card" was to leave all his victims naked with the exception of jewellery.
Mr Gull was asked about several of these by reporters during Thursday's news conference and he responded politely but firmly, taking care not to exclude most of the suggestions.
Suffolk Police is getting significant support from experts outside the county.
The national police training agency, Centrex, has deployed a crime operational support team to assist and offer additional expertise.
A Centrex spokeswoman said: "The team is a regional response team of experts experienced in dealing with serious crime investigation including murder, rape, abductions and serious sexual offences.
"These include a behavioural investigative advisor and a geographic profiler who are providing appropriate tactical advice to assist the investigation."
Another expert who has been called in is Patricia Wiltshire, a botanist who worked extensively with Cambridgeshire police during the Soham murders inquiry.
Ms Wiltshire, dubbed "the pollen lady", is an expert in the growth of plants and weeds and her help proved crucial in ascertaining exactly how long the bodies of Holly Wells and Jessica Chapman had been at the disposal site at Lakenheath.
She also provided crucial evidence about spores which linked Ian Huntley's Ford Fiesta to the track at Lakenheath.
One fear is that, with the huge police and media presence in Ipswich, the killer may be tempted to target prostitutes in other red light districts, such as Norwich or London.
Peter Sutcliffe claimed his first five victims in Leeds and Bradford
That is exactly what happened with the Yorkshire Ripper. Sutcliffe claimed his first five victims in Leeds and Bradford, both cities that he knew well.
But as the police and media interest in West Yorkshire grew, he travelled to Manchester to kill his sixth victim, Jean Jordan.
Mr Gull conceded on Thursday it was possible the killer could be displaced.
He said: "In all probability those responsible have some form of transport.
"We have liaised with our regional neighbours and they are putting preventative strategies in place in neighbouring counties and beyond."
Mr Dixon echoed that fear but added: "Displacement can happen. Clearly in this case there appears to be a degree of local knowledge and there is a comfort factor for the offender.
"If the offender is displaced it may be to an area he does not know so well and there may be a reticence to offend."
Were that to happen there would perhaps be the possibility that the killer, in an unfamiliar environment, could slip up.
Sutcliffe was arrested in 1980 when he picked up a prostitute in Sheffield, the first time he had chosen to target that city's sex workers.
While the momentum is there the police have a good chance of solving the murders.
The fear is that if, after a few weeks, there are no developments and no plausible suspects come to the fore, the inquiry may lose momentum and the leads may peter out.
All will be hoping that Mr Gull gets his man before that happens. Otherwise Ipswich faces an anxious festive period.