The back streets off Thornton Road, where many of Bradford's prostitutes ply their trade, were unusually empty last night.

The brutal murder of 19-year-old Rebecca Hall has sent shock waves among the community of women who earn their living in the area.

Following the discovery of Miss Hall's naked body in Thornton Street last Thursday, many working girls appeared to have been following police warnings by staying away.

Financial necessity, however, forced women like Susan, 22, and Miranda, 20, back on to City Road and its surrounding streets.

Susan, who has been working as a prostitute for four years, said: "Everyone's been terrified since we heard about the murder, it's the kind of thing you always know could happen with a punter, but you pray it won't.

"We've only just started working again but we're keeping an eye on one another."

Miranda, who admitted she has been "not long" in the business, said: "It's always been risky but when something like this happens it's really scary, it makes you think twice.

"But you've got to make a living and we've got people looking after us and they've promised to make sure we're all right."

Detective Chief Superintendent Max McLean, who is leading the investigation into the murder, has advised prostitutes in the city to keep off the streets or, at least, be more security conscious.

But there was no obvious sexual motive for the attack on Miss Hall, he said, and police think the killer may be someone who knew her outside of prostitution.

They believe Miss Hall, known as Becky to her friends, could have been abducted and held against her will after she was last seen leaving her flat in Little Horton on Good Friday.

She was found dead from severe head wounds in an alleyway yards from where she walked the streets in Thornton Road in the Lister Hills area.

But Detective Chief Superintendent Max McLean revealed today that forensic scientists believe the spot in Thornton Street where she was found was probably not the murder site.

He said: "What the scientists tell us at the moment is that Becky wasn't killed where her body was dumped.

"We are therefore trying to establish a murder scene. If anybody has any suspicions as to where a woman might have been held I would urge them to contact us.

"As I have said before, detectives in Bradford are not interested in what circumstances you knew Becky, just come forward and any information will be treated in the strictest confidence."

The detective said despite public appeals for information, there had been no confirmed sightings her after Good Friday.

Her body was found 13 days later but a forensic examination revealed she had been dead for four days at the most and officers believe she may have been held against her will.

He said prostitutes had been helping detectives with their inquiries.

"They're obviously assisting in terms of people they consider suspicious, that they may have met while they were working," he said.

"One of the things we are getting from the women is that Becky was one of the nice girls and very popular with her fellow prostitutes."

Anyone with information, or who knew Miss Hall, should contact the freephone number on 0800 318001.