In this study, it was found that false confessions in recent Japanese retrial cases were related to human interviews focusing on Linguistics structure. This study analyzed the case of the Japanese retrial case, the Asikaga case, in Forensic linguistics. In particular, the suspect of the Asikaga case appears to have considered the specific appropriateness of the investigator's question. This was claimed by Austin (1962), indicating that the result of the interaction of the participants was a ‘Speech Act’. The ‘Speech Act’ appears through repeated and induced questions from the investigator, and the suspect has no choice but to answer such questions. This means that even in the same sentence, the sentence is interpreted differently by considering the context in which it is actually spoken. In this study, the actual case analysis analyzed a series of questions from investigator and interviews with suspect in a series of Forensic linguistic analyses, and found the following results. This study, with the Forensic Linguistics approach Discourse Analysis, was able to analyse the false confessions as a ‘conformity condition’ referred to by the recognized Austin (1962). This could be described as an ‘locutionary act-illocutionary act-perlocutionary act’. In the future, it is expected to be a basic study of Forensic linguistics, which investigates the risk of rapport building as a question of the investigator in an investigative interview that prevents suspects from making false confessions.