The relationship of the ancient historian to his sources has not infrequently been compared to detective work. When the problem in hand is to discover the circumstances surrounding a murder, it is little wonder that ancient historians delight in retreading the same ground, encouraged by the absence of a final solution. There are a number of such mysteries thrown up by the world of antiquity, some more mysterious than others. Often there is the problem that at least one major suspect in some sense succeeded the victim in power, a dual problem in fact, since if guilty, the successor could cover up his tracks, if innocent, but nonetheless beneficiary of the death, he would incur suspicion anyway. I use the masculine pronouns, but female involvement is frequent — think of Livia and Agrippina. The case in hand is such as to excite curiosity: there seems to be an amount of evidence sufficient for a solution and the involvement of Alexander III raises tantalizing questions. Nor do we lack modern parallels to add spice to our investigation. The attempt to explain the assassination of President John Kennedy continues. Was there one gunman or, as now seems likely, two at least? Does that point to a conspiracy? There are further and more remarkable suggestions which, whatever their validity or otherwise, show a similarity with our case.