Venice had in its employ a spy and intriguer, the Cretan adventurer and businessman David Mavrogonato, regarded as a malshin (moser) by the Jews of his native Heraklion, who was engaged in furthering Venetian interests in the Ottoman Empire's dominions in the Aegean.
Both groups competed as suppliers of credit, but the older Italian Jewish communities quickly lost out to the new Yiddish-speaking Ashkenazi, and were forced to close down their banking operations in many northern areas in consequence.
Toaff describes entrepreneurs from these Ashkenazi communities as brash with the new power of the financial authority they had expeditiously acquired in a mere five decades after their arrival:- '(They were) self-confident and often arrogant and insolent in their relationships with rulers, observing laws only when it was strictly necessary or too dangerous to act otherwise.
The first was distinguished for his braggart haughtiness - he was defined by Venetian authorities as fidelis noster civis, and was assured of that city's protection - sufficiently so to boast of taking on and beating any Christian who might prove bold enough to mess around with him.
The other son, Salamoncino, took care of that grey area where shady business ventures and the criminal underworld rubbed elbows,[5] attempting to assassinate Mehmed II, dealing in counterfeit goods and forbidden trade, and fleecing the Jews of Padova, rabbis, widows, students and the poor, of their savings.
Tobias of Magdeburg, one of the doctors visiting Venice in search of a conferment of an imperial recognition from Frederick III in 1469, gave testimony linking the German Jews who had flocked to that city in the Emperor's train, with the figure of David Mavrogonato.
Specifically, Tobias testified that the German Jews were keen to procure from the daring Cretan trader the blood of Christian children, not for confectioning rare medicines, but rather for obscure magical religious rites.
According to further testimony by Israel Wolfgang, a double-dealing opportunist, powdered blood from Mavrogonato's shipment had been used in preparing the wine and unleavened bread for the Passover feast in Salomon of Piove's home, in 1471.
Reactions to the book concentrated on the final chapter, which addressed the story of Simon of Trent, a young boy supposedly murdered by Jews in order to extract his blood to be used in making bread for Passover rituals.
Shortly after its publication, press reports were circulated stating that Toaff claims in his book that there was some truth to the story, and that Christian children may have been killed by "a minority of fundamentalist Jews of Ashkenazi origin."
On the central case for his argument, which is that of Trent, he does not bring new documents but tries to overturn the scientific methodology used for decades for the correct interpretation of known and public ones, without realizing that, using his method, one would also have to admit that witches rode broomsticks to meet the Devil, or that hundreds of good 1990s Americans were kidnapped by little green men from some distant galaxy".
Toaff added an afterword, "Trials and Historical Methodology: In defence of Pasque di Sangue", in which he wrote, I wish to specify that the principal aim of my research was to investigate the role of the so-called ‘blood culture’ in the German-speaking Jewish community, as in the Christian society that surrounded it.