In the "Ace Attorney" series, who was the truly responsible of the forging of the autopsy report of the pivotal IS-7 incident?

In the Ace Attorney series, Bansai Ichiyanagi is truly responsible for the forging of the autopsy report of the pivotal IS-7 incident. This is revealed during the course of the game through various pieces of evidence and witness testimonies that point towards Bansai as the culprit. His motive for forging the report was to cover up the true cause of death and protect his family's reputation.