British police, hunting a serial killer who has murdered five prostitutes, are poring over 10,000 hours of CCTV footage and trying to trace some 50 to 100 people.
Police in eastern England, where the murders occurred, hope to issue images over the weekend of some of the women to try to help determine their movements in the hours before their deaths, assistant Chief Constable Jacqui Cheer said.
Suffolk Police handout CCTV footage, dated Sunday December 3, showing murdered prostitute Anneli Alderton on the 5.53pm train from Harwich to Colchester
"We are feeling confident about the inquiry," Chief Constable Cheer told the BBC. "We're getting lots and lots of information in."
She said police hoped to release some images on "Saturday and Sunday which will help us trace the last movements, particularly of Anneli Alderton".
She confirmed that Alderton (24) was three months pregnant when she was murdered. The murderer has been dubbed the Suffolk Strangler, although the precise way all the women died is yet to be established.
Prostitutes in the region are being offered financial help to stay off the streets but some have ignored police warnings and carried on working, many to feed drug habits, despite the discovery of the five bodies in less than two weeks.
Alderton was strangled and Paula Clennell, 24, was killed by "compression to the neck". The police inquiry began on Dec. 2 when the body of Gemma Adams, 25, was found in a stream near Ipswich.
Police found 19-year-old Tania Nicol's body in the same stream on December 8th. Police on yesterday confirmed prostitute Annette Nicholls as the fifth victim. Nicholls (29), was last seen on December 5th, a week before her naked body was found dumped in countryside.
No one has yet been arrested or questioned as a suspect, but police were seeking a number of people to help with their enquiries.
"We wouldn't use the word suspects, but we are talking to a number of people," said Chief Constable Cheer, who added police are considering holding reconstructions into some of the murders.
The case has echoes of those involving the 19th century prostitute killer Jack the Ripper, who was never found, and Peter Sutcliffe, the Yorkshire Ripper, who killed 13 women, mainly prostitutes, in northern England between 1975 and 1980.