noun
offender; criminal; perpetrator
Dated term, especially used historically for a murderer or the person who committed a crime. In modern contexts, 犯人 or 加害者 is more common.
江戸時代の文書には、下手人として名が記されている。
In Edo-period documents, his name is recorded as the offender.
下手人はすでに捕らえられたと聞いた。
I heard that the perpetrator had already been caught.
加害者 means 'perpetrator' or 'offender' in a legal or victim-focused context. 下手人 is archaic and not used in modern legal settings.
Compound of 下手 (geshu, 'to carry out' or 'to do') and 人 (nin, 'person'). The exact historical derivation is uncertain, but it has been used in legal and historical contexts to refer to a person who committed a crime, especially murder.