Leading expert on sex offenders, Ray Wyre, has died following a stroke aged 56.

Mr Wyre worked with some of the most dangerous criminals, including Reggie Kray and child killer Robert Black.

His background was in probation but he was called in to many of the biggest murder cases.

Mr Wyre questioned Anne Marie West as officers prepared the case against her parents, Fred and Rosemary.

His work with TV journalist Roger Cook was key in child pornography being made illegal in 1987 and he founded the world's first residential treatment centre for sex offenders.

Dick Monk, ex-Assistant Chief Inspector of Constabulary at the Home Office, said: "It's a tragedy for law enforcement. He is irreplaceable."

Police believe Wyre's taped interviews with Black could yet prove crucial as they seek to solve the 1978 murder of 13-year-old Genette Tate.

In recent years Mr Wyre spent some of his time playing on the professional poker circuit.