A detective investigating the murders of three prostitutes has appealed to the killer to give himself up.
Detective Chief Superintendent Stewart Gull said: "Make contact with Suffolk Police. Clearly you have a significant problem. Give me a call and we can deal with this.
"My appeal is simple. Give yourself up."
Mr Gull said he had "grave concerns" for the safety of two other women who have not been heard from since Sunday.
Paula Clennell and Annette Nicholls have not contacted police, despite urgent public calls for them to get in touch.
Mr Gull said: "I have grave concerns for their welfare. There have been other girls reported as missing who have subsequently been found. I hope Paula and Annette are just lying low for whatever reason.
"If anybody knows their whereabouts, then get in touch."
Mr Gull said the officers were investigating the possibility that the three murdered women had been poisoned.
He said: "That is possible. 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."
He urged prostitutes to stay off the streets. "Now we have three murdered girls. Our advice is stay off the streets, stay at home," he said.
