When adjustments in terms of Church procedure or the expelling of "sinful" individuals such as prostitutes did not rid towns of the plague, people started to blame Jews for being the reason the Back Death was so rampant. Accused of poisoning water sources and families with the pestilence, Jews were interrogated, tortured, and executed all throughout the European continent. Jewish conspiracies were classified as secular crimes, however many of them were burned at the stake, a practice rooted in the Inquisition (Black Death Overview, 34).
Unlike the peasants, many top Church officials forcefully condemned these killings, including Konrad of Megenburg, Heinrich of Herford, and Pope Clement VI (Black Death Overview, 35). Clement, specifically, used a previously written papal bull, Sicut Judeis, to defend his position. Along with reissuing this document in 1348, Clement granted priests excommunicative authority if peasants did not obey the order to stop Jewish persecution. He also reminded priests that Jews facing accusations deserved a fair trial (Horrox, 221-222). These strong condemnations of Jewish persecution are notable because many Church figures, such as St. John Chrysostom in the 4th century, had previously seen Jews as reprehensible and responsible for the death of Jesus (Gilman and Katz, 47).
Sources
Black Death Overview, pages 34-35.
Sander L. Gilman and Steven T. Katz. Anti-Semitism in Times of Crisis. New York: NYU Press, 1993.
"Mandate of Clement VI Concerning the Jews." In The Black Death, edited by Rosemary Horrox,
221-222. Iowa: Manchester University Press, 1994.