Abstract: In 1844, Joseph Smith, founder of The Church of Jesus Christ of Latter-day Saints, was assassinated in Carthage, Illinois, along with his brother, Hyrum. Much has been written about the assassination of Joseph and Hyrum Smith, but little attention has been paid to the crime scene in Carthage Jail. This article examines eyewitness accounts of the assault, the layout of the crime scene, the physical evidence left in the jail, and the types of weapons used and the wounds they inflicted on the Smith brothers, John Taylor, and Willard Richards. This multidisciplinary investigation of the martyrdom examines the accuracy of the firsthand accounts of the Willard Richards and John Taylor and evaluates the crime scene. Moreover, the surviving physical evidence is consistent with an assault by men armed with 69-caliber muskets, the standard musket issued to militia units in Illinois. The military muskets were used is supported by Willard Richards's mention of bayonets, by the diameter of the bullet holes in the door, by the diameter of the bullet holes in Hyrum Smith's clothing and face and by the dent in his watch.