Alexander Suslin HaKohen ( died 1349 ) was a prominent 14th century rabbinic authority born in Erfurt , Germany , and one of the most important Talmudists of his time . He was rabbi first in Cologne and Worms , and then moved to Frankfort-on-the-Main . He authored '' Sefer HaAguddah '' ( ספר האגודה , " Book of the Collection " ) , a halakhic work ( structured by the order of the Talmud 's tractates ) which was highly regarded by later rabbinic authorities . He was killed in the Erfurt massacre of 1349 during the Black Death era massacres of hundreds of Jewish communities throughout Europe
Erfurt massacre of 1349
Erfurt massacre (1349)
Alexander Suslin