According to Yofumi TAMANO, the judge who judged them,it seems that all but the principal offender, Ichiro SHIMADA did not know the objective of the assasination and commited the crime because they were brainstormed by SHIMADA to believe that 'it was for the country to get rid of this person' (Tokyo Daily Newspaper, June 1st, 1878).
彼らを裁いた判事・玉乃世履によると、主犯の島田一郎以外はこの暗殺の趣意を知らず、ただ島田に「この人を除く事が御国のため」と洗脳されて犯行に及ぶに至ったと思われるという（東京日日新聞・明治11年6月1日）。