The two bodies found Tuesday have not been identified, but the detective leading the investigation said it was likely they were those of Annette Nicholls and Paula Clennell, two prostitutes who had been missing for days.
Detective Chief Superintendent Stewart Gull of Suffolk police advised Ipswich prostitutes not to go out to work.
"We have got three prostitutes murdered, now possibly another two. I do not know what stronger warning there can be to get off the streets as soon as possible," he said.
Detectives were already investigating the deaths of three women, whose naked bodies were found a few miles apart. One body was found in a stream, another in a pond and a third in the woods, about 30 yards from a road.
The two bodies discovered Tuesday were lying near Levington, Suffolk, a village about five miles south of Ipswich. The corpses of the five dead women all have been found within a few miles of Ipswich.
The killings have stirred memories of the so-called Yorkshire Ripper, one of Britain's worst serial killers. Peter Sutcliffe admitted to killing 13 women, mostly prostitutes, in the 1970s. He was sentenced to serve a minimum of 30 years in prison.
His reign of terror recalled Jack the Ripper, the notorious Victorian serial killer who murdered at least five East London prostitutes in 1888. He was never caught and speculation about his identity continues.
The latest deaths have drawn intense media interest, with Ipswich's afternoon newspaper labeling the prostitutes' killer "the Suffolk Strangler."
Police said they suspected a serial killer in the Suffolk cases, but were not ruling out multiple suspects. Police said there was also no indication women other than prostitutes were targeted.
The three victims who have been named were identified as Gemma Adams, 25, whose body was found Dec. 2; Tania Nicol, 19, whose body was found Friday; and 24-year-old Anneli Alderton, whose body was found Sunday. Police said Alderton — who was last seen on a train — was asphyxiated. It appeared she had been strangled and that she was not sexually assaulted, police said.
The condition of the bodies of Adams and Nicol — both of whom were found in water — has prevented investigators from determining a cause of death or whether they were sexually assaulted.
Nicholls, 29, was last seen Dec. 5; Clennell, 24, was last seen Sunday. The women, both prostitutes, were seen in the neighborhood in the shadow of the town's soccer stadium, where sex workers ply their trade.
Police were reviewing closed-circuit television video of the small district — just a few blocks square — and other areas of Ipswich, which is about 70 miles northeast of London.
Ian Hunter, a 46-year-old who works for telecom company BT — one of Ipswich's main employers — said that he had been fishing on Sunday in the area where Alderton was found.
Normally, Ipswich — a town of about 120,000 — is "pretty relaxed," Hunter said, but the murders have set residents on edge.
"My daughter is 13, and once a month, they have a youth club (in town). And she won't go," Hunter said. "There's supposed to be one this Friday, but she won't go.
"My wife works in town, and they've been told to only move about after dark with a friend."