Night before Execution

It is an accepted tradition that the lengthy Tosfosim in the seventh perek of Bava Kamma were authored by the Baalei HaTosfos the night before they were murdered al pi Kiddush Hashem. While they were imprisoned, knowing that they would be killed the next day, they occupied themselves by delving into the depths of Torah. It is said that they cut their fingers and used the blood for ink. “Mi k’amcha Yisroel?”