It's happened at least once, though in papal court not criminal: https://en.wikipedia.org/wiki/Cadaver_Synod https://en.wikipedia.org/wiki/Cadaver_Synod Though

It's happened at least once, though in papal court not criminal: https://en.wikipedia.org/wiki/Cadaver_Synod https://en.wikipedia.org/wiki/Cadaver_Synod Though I would be surprised if not once in human history in some kangaroo court a dead person was put on trial for a crime. edit: Here's one though it resulted in a mistrial https://en.wikipedia.org/wiki/Henry_Plummer https://en.wikipedia.org/wiki/Henry_Plummer