Detectives hunting the killer of a Shipley housewife are hoping a nationwide appeal will provide the key to solving a 23-year-old mystery.

A reconstruction of Mary Gregson's last steps in August 1977 and ensuing search for her murderer will feature on BBC's Crimewatch UK programme later this month.

The case was re-opened in September last year after advanced DNA techniques gave police a genetic profile of the killer.

Detectives revealed today that 400 people had now been eliminated from the original list of 9,000 possible suspects, drawn up in the late 1970s.

Senior investigating officer Detective Chief Superintendent Brian Taylor said: "We are continuing to work our way through the list, but many of the possible suspects suggested to officers 23 years ago will have moved from the Shipley area.

"The nationwide Crimewatch appeal might just jog someone's memory and give us that vital clue we have been looking for."

Ch Supt Taylor said information was continuing to pour in from members of the public.

"It proves people are still thinking about the events of 1977 and are now willing to contact the police," he said.

He said because there was already a DNA profile of Mary's killer, suspects would only need to undergo a simple swab test for elimination purposes.

Mary, 38, was sexually assaulted and strangled as she walked to work along the Leeds-Liverpool Canal towpath on August 30, 1977.

He body was found the next morning in the River Aire near Salt's Mill, a few hundred yards from the cottage in Jane Hills she shared with her husband Bill and 11-year-old son Michael.

Yorkshire Ripper Peter Sutcliffe has already been eliminated from the police inquiries along with 750,000 other convicted criminals on the national DNA database.

l The Mary Gregson appeal will be shown on Crimewatch UK, BBC1 on January 25. Anyone with information about the murder can contact the Shipley incident room on (01274) 537422 or Crimestoppers on 0800 555 111.

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