Recent discoveries in botanical sciences have found a possible plant that fits the symptoms of Alexander the Great's death.
What are some prominent theories on who would be behind such a plot to murder him (I'm sure there were many states that wanted him dead), and why (what did they have most to gain at his death)? Although I'm less inclined myself to believe, I know one theory posits Aristotle as a possible conspirator.
http://www.historytoday.com/james-romm/who-killed-alexander-great
of course I had to pay for it.
Greek theories at the time purpoted Antipater, who may have sent Cassander to see him with Styx water that may have contained Calicheamicin.
Cassander went on to kill Alexander's mother and supposed heir later on.
However, the article gives many other theories, and mentions that Macedonian General's were not known for using poisons (i.e. had little or no knowledge on them). Many theories... one of which that Aristotle may have helped Antipater due to Aristotle's own relative's death that Alexander sanctioned, Callisthenes.