Qin Shi Huang Di was a man who was obsessed with immortality. His prime ministers and other palace healers made him a pill to take that contained too much mercury in it and he died from organ failure, mostly kidney and liver. None know how or why he became so obsessed with immortality, but scholars assume that the mercury and other various drugs in the pill cause Qin Shi Huang Di to become paranoid and start hallucinating. Few knew of this, and those that did kept it secret because they were members of the Rebels: they didn't like the way Qin Shi Huang Di was so cruel and strict. The few members of the Rebels that did know later were found out about and executed for high treason. They were executed using Qin Shi Huang Di's favorite method: torn apart from limb to limb by horses. You litterally had your arms and legs torn from your torso and you died from lack of blood. The death of Qin Shi Huang Di is only labeled as a mystery because few know of the real storry of what happened to the emperor and his decendents. Scholars believe that his decendants were later assassinated.