“I’ll tell the police about you,” a 14-year-old girl told a motorist who offered her 10 shillings to go with him in his car in Maltby, Yorkshire. The motorist drove off rapidly. Six days later, on Wednesday, May 6th, 1964, 13-year-old Anne Dunwell set off to catch a bus from her grandparents’ home in Rotherham.

Anne never boarded the bus. At 7.30 next morning her nude corpse was found by a labourer on his way to work. It had been dumped by a dung heap in Slade Hooton Lane, near Maltby. She had been raped and strangled with her stockings.

“We have a beast at large who has killed once and will possibly try to kill again,” a senior police officer announced. The hunt was on for the owner of a rusty, brown-coloured van that had been seen near the Ball Inn on the night of the murder. It had been converted into a mobile shop, taller and squarer than a normal van.

The man was never found and for nearly 40 years the file lapsed. Then in November, 2002, forensic scientists re-examined the knots in Anne’s stockings, fibres from her clothing, and bacteria found on her underwear. As a result of that examination, said a police spokesman, “we have reason to believe that the killer was suffering from gonorrhoea.”

So were there any local residents able to recall a partner or friend who 40 years previously had confided that they had the disease? The police were certain that there was someone out there who could put all these pieces of information together and come up with the killer’s identity.

Witnesses came forward. There was a stranger, they said, drinking brandy in the Ball Inn at the time of the murder. He had a soft Scottish accent, went by the name of Pete, of average height, slim, with well-groomed hair. He smoked Craven A cigarettes and was apparently single.

All that, of course, was 40 years ago. Today he would probably be paunchy and grey-haired. Or would he? For on May 6th, 2004, the 40th anniversary of the murder, police announced that they had narrowed down the suspects to two. Both were sex offenders, and one had been convicted of murder. And both were now dead.