Johannes Pfefferkorn, born a Jew, possibly in Nuremberg, had moved to Cologne after many years of wandering.
After committing a burglary in 1504, he had been imprisoned and released.
Converting to Christianity in 1505, he had been baptized together with his family.
Pfefferkorn had then become an assistant to the prior of the Dominican friar order at Cologne, Jacob van Hoogstraaten, and under the auspices of the Dominicans had published several libelous pamphlets in which he tried to demonstrate that Jewish religious writings are hostile to Christianity.
He demands in Der Judenspiegel (Cologne, 1507) that the Jews should give up the practice of usury, work for their living, attend Christian sermons, and do away with the books of the Talmud.
On the other hand, he condemns the persecution of the Jews as an obstacle to their conversion, and, in a pamphlet, Warnungsspiegel, defends them against charges of murdering Christian children for ritual purposes.
In Warnungsspiegel, he professes to be a friend of the Jews, and desires to introduce Christianity among them for their own goo.
He urges them to persuade the Christian world that the Jews do not need Christian blood for their religious rites and advocates seizing the Talmud by force from them.
Bitterly opposed by the Jews on account of this work, he virulently attacks them in Wie die blinden Jüden ihr Ostern halten (1508); Judenbeicht (1508); and Judenfeind (1509).
In his third pamphlet, he contradicts what he had written earlier and insists that every Jew considers it a good deed to kill, or at least to mock, a Christian; therefore he deems it the duty of all true Christians to expel the Jews from all Christian lands; if the law should forbid such a deed, they do not need to obey it: "It is the duty of the people to ask permission of the rulers to take from the Jews all their books except the Bible...."
He preaches that Jewish children should be taken away from their parents and educated as Catholics.
In conclusion he writes: "Who afflicts the Jews is doing the will of God, and who seeks their benefit will incur damnation."
In the fourth pamphlet, Pfefferkorn declares that the only way to get rid of the Jews is either to expel or enslave them; the first thing to be done is to collect all the copies of the Talmud found among the Jews and to burn them.
He obtains from several Dominican convents recommendations to Kunigunde, the sister of the Emperor Maximilian, and through her influence to the emperor himself.
Maximilian, who already had expelled the Jews from his own domains of Styria, Carinthia, and Carniola, orders the Jews on August 19, 1509, to deliver to Pfefferkorn all books opposing Christianity; or the destruction of any Hebrew book except the Hebrew Bible (Old Testament).
Pfefferkorn begins the work of confiscation at Frankfort-on-the-Main, or possibly Magdeburg; thence he goes to Worms, Mainz, Bingen, Lorch, Lahnstein, and Deutz.
The Jews, through the help of the Elector and Archbishop of Mainz, Uriel von Gemmingen, ask the emperor to appoint a commission to investigate Pfefferkorn's accusations.
A new imperial mandate of November 10, 1509, gives the direction of the whole affair to Uriel von Gemmingen, with orders to secure opinions from the Universities of Mainz, Cologne, Erfurt, and Heidelberg, from the inquisitor Jacob van Hoogstraaten of Cologne, from the priest Victor von Carben, and from Johann Reuchlin.
