Being accused of assassinating Ryoma SAKAMOTO, Oishi was subjected to violent interrogation and, at one point, admitted guilt unable to bear the pain any longer, but subsequently retracted his earlier testimony insisting that the assassination was carried out by Mimawarigumi.
坂本龍馬暗殺の嫌疑をかけられた大石は、厳しい詮議に耐え切れずに一度は「自分がやった」と証言するが、後に前言を撤回し見廻組の仕業であるとしている。