According to one theory, on learning of Izo's arrest, TAKECHI became afraid that Izo's confession may put his comrades on line, and he even tried to poison Izo through a jail keeping government official who was devoted to TAKECHI.
一説によれば、以蔵の捕縛を知った武市は彼の自白によって他の同志が危険に晒されるのを恐れ、自分に心酔した牢役人を通じて以蔵に毒を盛ろうとしたとさえ言われている。