While the destruction of the Nauvoo Expositor in June 1844 played a role in the martyrdom of Joseph Smith in Carthage, Illinois, on June 27, 1844, there were other factors. These included fear of the Nauvoo Legion's power and the concentration of power in Joseph Smith himself, economic competition with some of the leading Mormon opponents, and political unrest due to the rapidly increasing Mormon population in and around Hancock County. Less known is the legal charge of treason issued by a judge on June 26, as well as a series of misdemeanor cases that were raised against Joseph during his last few weeks, and a previously unpublished series of posthumous civil actions relating to the Nauvoo Expositor. This study documents and analyzes the legality of each of these court actions, concluding that these legal maneuvers and other efforts were ill-founded and intentionally designed by the organizers of the Nauvoo Expositor mainly to place Joseph Smith’s life in mortal danger in Carthage. It also provides more detailed background on the men behind the Expositor who directly contributed to the Prophet’s incarceration and death.