What were the reasons people thought Kabuo Miyamoto was guilty?

An odd wound on the left side of his head triggered an investigation into the death of Carl Heine. The coroner, upon examining the wound, stated that it reminded him of the wounds made in close combat with the Japanese during the war, often made by kendo techniques. Additional evidence points in the direction of Kabuo and Carl having had an encounter that night on the sea: the mixture of engines between their boats, a mooring line on Carl's boat that resembled all of Kabuo's, and the presence of Carl's blood on the handle side of a rope with a fishing gaff, which the prosecution hints was the murder weapon. Each piece of evidence is challenged by the defense attorney, Nels, to shed doubt on the prosecution's case.