West Yorkshire's top detective is moving on after more than 30 years' service, which has seen him lead successful investigations into some of the biggest crimes in recent Bradford history.

Detective Chief Superinten-dent Chris Gregg, who headed the Force's Homicide and Major Enquiry Team, is moving on to a new challenge as a major crime adviser to a leading forensic service provider company.

Det Ch Supt Gregg joined the force in 1974 and as a rookie constable was put on front-line duties in the Yorkshire Ripper inquiry in the Helen Rytka murder incident room.

As a young detective he investigated three of the later murders, including that of Bradford University student Barbara Leach.

Thirty years later, Det Ch Supt Gregg had the satisfaction of getting the conviction of John Humble - the Ripper hoaxer who led the investigation team down the wrong path.

As a detective superintendent, and senior investigating officer for the western side of the county, Chris led the investigation into the murder of 26-year-old Dexter Coleman, who was gunned down outside the Young Lions Cafe, in Lumb Lane, Manningham, in July 2000.

Mr Coleman was shot as he fled a 100-strong mob. Safdar Khan, 23, of Girlington, was jailed for life for the murder.

Mr Gregg also investigated the attempted murder of prostitute Nicola Hirst in October 2000. She was stabbed more than 40 times and left for dead by convicted murderer Noel Dooley in Bradford's Lister-hills red light area.

He also led investigations into the murder of Bradford traffic policeman Ian Broadhurst and the case of killer nurse Colin Norris.

Det Ch Supt Gregg said yesterday: "I have had a fantastic career in West Yorkshire and have been honoured and privileged to serve with the force, which has some remarkable people doing remarkable jobs, often in the most difficult of circumstances.

"But I am looking forward to a fresh challenge with LGC Forensics, where I will be working alongside scientific teams on some of the major cases in the country."

He said advances in science and technology, like DNA, had greatly helped in detecting crimes.

He said: "Scientific technology is hugely important, but it is still only an aid to good old-fashioned detective work which remains the cornerstone of police investigations."

He said the police service would always welcome additional funding to bolster resources.

But he said: "We have to work with what we have. The funding pot is not a bottomless pit.

"We have to cut our cloth accordingly and that is what we do, while making sure our priorities are fully met."

Det Ch Supt Gregg said the convictions of John Humble, Colin Norris and David Bieber, the murderer of PC Broadhurst, were among the most satisfying of his 33-year career with the West Yorkshire Force.

Chief Constable Sir Norman Bettison said: "Chris stands alongside some of the great investigators that West Yorkshire Police has had. He is going to be a hard act to follow."

Det Ch Supt Gregg was leaving the force today. His successor has not yet been announced.