Police investigating the murders of three prostitutes near Ipswich say the third victim was strangled.
Miss Alderton's naked body was spotted by a motorist
The body of Anneli Alderton, 24, was found in woodland at Nacton on 10 December. Tests are being carried out to see if she was sexually assaulted.
The bodies of two others, Gemma Adams, and Tania Nicol, were found near Ipswich, within the last 10 days.
Suffolk police confirmed they are searching a fourth location around the village of Levington, near Ipswich.
The woodland area is close to Nacton where Anneli Alderton was found on Sunday.
Police say they have "grave concerns" for the safety of two other women - Paula Clennell and Annette Nicholls.
The pair, aged 24 and 29, have not been heard from since Sunday and police have urged prostitutes to stay off the streets.
Miss Clennell, who gave a television interview just days before she went missing, said she was prepared to face the perils of going back on the streets.
The killings had made her a bit wary about getting into cars but she would still do it, she told ITN.
Det Ch Supt Stewart Gull said officers are also investigating the possibility the victims had been poisoned.
"We are doing toxicology tests along with a number of other clinical and scientific analyses following the post-mortems and we will do the same with the latest victim."
There were no signs of asphyxiation on Gemma Adams and Tania Nicol, he said.
Mr Gull called on the killer to give himself up, saying: "Make contact with Suffolk Police. Clearly you have a significant problem. Give me a call and we can deal with this."
Initial police inquiries revealed Miss Alderton, from Colchester in Essex, caught the 1753 GMT train from Harwich to Colchester on 3 December.
There are no known sightings of her alive since then.
A passing motorist believes he saw the body in situ on 7 December.
However, he thought it was an abandoned mannequin and did not report it to police.
"It is important that we try to piece together Anneli's final movements. We know that, like Gemma and Tania, she did work as a prostitute in Ipswich. However, unlike them, she had not been reported missing," Mr Gull said.
Officers spent another night patrolling the red light area of Ipswich where about 30 prostitutes are thought to work regularly.
Detectives want to hear from them all and find out clients' names.
Annette Nicholls, 29, was reported missing by her family
Mr Gull said: "Streetworkers and the men who go with prostitutes probably hold the key.
"We have had a tremendous response from streetworkers. Some limited contact from punters."
The body of Ms Adams was found on 2 December at Thorpes Hill, Hintlesham, near Ipswich.
Police divers recovered the body of Ms Nicol six days later from the same stretch of water at Copdock Mill.
The body of Anneli Alderton was found in an area of woodland at Nacton on 10 December.
Police have also begun checking the whereabouts of nearly 400 registered sex offenders in Suffolk.