Who Killed Alexander?

I'm guessing Drelzna, disguised as Olcias, with Styx water hidden in a false foot of some sort.

From the Diadocomachia: Menander, who was the father of the notorious page Charicles, had just arrived in Babylon the day before the fatal dinner party, bearing with him the prisoner Diodorus the Ephesian, assassin of Hegesias. Others say another assassin, arrived in his company, but she in disguise.

In disguise, some say, she attended Medius the Sycophant’s dinner party.

From Eumenes' List of Suspects: Olcias: A friend of Medius', presumably? (Although frankly too old for the role.) Too much a nobody to pose any threat to Alexander. Walked with a limp going out that he had lacked going in, if I recall; but then, he drank immoderately.

And: Who was not at the party? Laomedon? Hercules? Harpalus had disappeared, I wish I knew where to. The women, of course, the wives, Roxanne and Strateira; some say Menander had arrived with the fat one-eyed bastard's wife in tow, but if so I never saw her. In any case, no woman was in the room, this much is certain, just as it is certain that no one was carrying an ass's hoof. The protections on Alexander counted for something.

From Fragments in Cassandreia: lcias had come from Nonacres, which lies near Ph

Now we must ask, why? Who was the intended target? Ptolmey?