A RETIRED policeman today re-lived his involvement in one of the most controversial police inquiries Britain has even seen -- and his satisfaction at catching The Beast of Blackburn.

In 1948, police painstakingly examined the fingerprints of 44,000 men until they caught the man responsible for the death of a three-year-old child abducted from the children's hospital ward at Queen's Park Hospital.

It was the biggest and possibly the most controversial fingerprint investigation in British history. Despite taking the prints of every man in the local community, the killer eluded the police.

Finally, they decided to try local serviceman posted outside the city.

It was among those 200-300 men that the murderer -- an ex-guardsman who claimed to have a history of schizophrenia -- was found. Peter Griffiths, 22, lived in Birley Street, Blackburn, and was later hanged at Liverpool's Walton Jail.

Arnold Hedley, 84, of Blackburn, was born in the residential Mellor Police Station in 1917.

He followed proudly in the footsteps of his father, Jack Hedley, who was a former police sergeant at the station.

It was just after the Second World War that Arnold joined Blackburn police force, where he stayed for 25 years before retirement.

It was just a few years later when he became involved in the investigations into the case that left the people of Blackburn in a state of complete shock.

Arnold said: "I had never been involved in a case like this before and was never involved in another murder case ever after this one, which is why it has stuck so vividly in my mind throughout all of these years. When the producers of a TV documentary series first approached me to be interviewed for a programme it involved re-living a lot of horrible memories that I had managed to push to the back of my mind for many years.

"I had an official report of the whole case which I had kept for the three months of work that I had done on the case so I went through that to go back to the crime and it opened up an army of old memories that were best kept in the report."

The case was described by Arnold as one of the most horrific scenes of murder that the police force in Blackburn had ever seen.

He said: "I will never forget what happened to that little girl.

"What we uncovered during the enquiries was unexplainable. It is good to see that, after the ground-breaking use of fingerprinting in Blackburn all those many years ago, it is still used today as a compelling source of evidence in many cases."

The case is to feature in a TV documentary shown tonight at 9pm.

Previous episodes have talked about the DNA revolution, an interrogation in the 20th century and profiles of the criminal mind.

Filmed in Britain, the United States, Argentina and the Bahamas, the series examines a century of highs and lows of groundbreaking crime-detection techniques that were used so many years ago.

Catching The Killers is the fourth programme in the five-part series of BBC-2 documentaries.