From the Jerusalem Post:
In the second half of the 12th century, a Jewish woman named Pucellina, presumably of Italian ancestry, had dealings with the nobility in the town of Blois, located in Champagne. Most likely she was a moneylender, not an unusual profession for a medieval European Jew with funds; colleagues of hers were lending money to members of the nobility as well as to the church.
A distressing incident, namely a false blood-libel claim, transpired on May 26, 1171, ending in disaster for Pucellina. A male servant was supposedly watering his horse by the bank of the Loire when he noticed a Jew nearby. According to his account, this Jew was tossing the body of a Christian boy he had murdered into the river. The servant was convinced that the entity thrown into the water was a corpse because his horse was so startled that it refused to drink.
This “witness” immediately reported his sightings to his master, who realized that he had been afforded a perfect opportunity to undermine the local Jewish community. In particular, he could undermine Pucellina, to whom he had a strong aversion; this arrogant Jewish woman had the gall to consider Count Thibaut (of Blois) her patron.