By Hugh Levinson
BBC Radio 4, producer of The Blood Libel
For hundreds of years, it's been said that Jews kill Christian children and drain their blood for ritual purposes. Why has this myth persisted for so long?
Mural of the ritual in a Polish church
Raya Beilis still remembers the day in 1911 that her father was arrested by the Kiev secret police, and put on trial for the alleged Jewish ritual murder of a Christian boy.
"I was too young to understand," says Raya, who now lives in a nursing home in New York City. "All I knew was that they said if he's guilty, they're going to kill every one of you."
The authorities in Kiev said Mendel Beilis had lured a teenager called Andrey Yustschinsky away from his family, killed him and drained his blood for the production of matzah, the unleavened bread eaten at Passover.
The court threw out the charges, which were clearly fabricated. Mendel Beilis was freed and the feared pogrom against the Kiev Jews never happened. But where did this bizarre accusation come from?
Mendel Beilis was acquitted in 1913
The origins of this anti-Semitic myth, known as the blood libel, lie in medieval England. In 1144 a skinner's apprentice called William went missing in Norwich. When his body was found, the monks who examined the corpse claimed that the boy's head had been pierced by a crown of thorns.
Some years later, a monk called Thomas began to gather evidence about William's death. His main aim was to establish the boy as a holy martyr and draw pilgrims to the cathedral. Almost as an incidental matter, he accused the Jews of Norwich of killing the boy.
"The unforeseen outcome of what Thomas did was to create the blood libel, which then itself takes on a life of its own," says Dr Victor Morgan, of the University of East Anglia.
Hysteria, not evidence
The accusation that Jews would drain the blood of children and then use it for ritual purposes is bizarre, as Judaism has a powerful taboo against blood. Indeed, kosher butchering is meant to remove all blood from meat. But the idea seems to have had a powerful hold on the mediaeval imagination.
"It's not just an act of murder and of a ritual murder," says Professor Robert Wistrich, of the University of Jerusalem.
The myth originated in East Anglia
"Removing the blood from the body and then using it for a ritual or religious purpose - there is something horrific, but yet as fascinating as it is repulsive in this notion."
The blood libel spread across England and Continental Europe over the centuries, with hundreds of accusations, all based on hysteria rather than evidence. There were notorious blood libel cases in Lincoln in 1255 and Trento, Italy, in 1475. Many Jews were executed. Others were killed by mobs seeking revenge.
There was another rash of accusations in the late 19th and early 20th centuries in Eastern Europe - societies gripped by economic transformation and political uncertainty, climaxing with the Beilis case of 1913.
Even though the blood libel has been disproved countless times, it refuses to fade away. Racist groups in the US still sell videos which maintain that Jews commit ritual murder.
The evil myth that just won't die
And the charge has now gained currency in the Arab world. The Syrian defence minister, Mustafa Tlass, has written a book repeating the accusation, while some journalists continue to use it as part of the rhetorical war against Israel.
Professor John Klier, of University College London, says this is a tactic that has backfired. The blood libel is now so discredited in the West, he says, that the people who use it are seen as outside the scope of rational political debate.
The Blood Libel was broadcast on BBC Radio 4 in the UK at 2000 GMT on Monday 26 January.