British police said they found two more bodies on Tuesday believed to be murdered by a possible serial killer targeting prostitutes, adding the death toll to five in ten days. 

(L-R) Murdered prostitutes Gemma Adams, Tania Nicol, Anneli Alderton, missing prostitutes Paula Clennell and Annette Nicholls (Photo source: Xinhua/AFP)

A head of the small local police force said his detectives were facing an "unprecedented" investigation as they attempted to solve five murders in and around Ipswich in eastern England.

Earlier on Tuesday, Detective Chief Superintendent Stewart Gull said he believed sex workers might have vital information that could help identify the murderer.

"I am convinced the working prostitutes in Ipswich probably hold the key as to who is responsible," he said.

The two bodies were found in the Nacton area to the east of the town close to where the naked body of Anneli Alderton, 24, was discovered in woodland on Sunday.

Gull said the bodies were probably those of missing prostitutes Paula Clennell, 24, who had not been seen since Saturday, and of 29-year-old Annette Nicholls, who had been missing for at least a week.

The massive police inquiry began on Dec. 2 when the body of Gemma Adams, 25, was found in a stream in the west of the town. Police divers then discovered 19-year-old Tania Nicol in the same stretch of water on Dec. 8.

Local police have warned prostitutes to stay off the streets and women have been advised not to go out alone.

The most notorious such killer was the 19th century murderer known as "Jack the Ripper," who was blamed for the deaths of five prostitutes in east London in 1888 but was never found.

The most prolific was Peter Sutcliffe, called the "Yorkshire Ripper," who murdered 13 women, mainly prostitutes, in northern England from 1975 to 1980 before he was caught.