Who is Responsible for the Death of King Duncan in ' Macbeth' by William Shakespeare? In the debate of responsibility for Duncan's death it would be rational to primarily consider his murderer, Macbeth. A number of factors lead him to kill Duncan. It is evident that he did not go about his crime acting entirely of his own accord - there is an element of corruption from the witches and his wife - however he must have had an existent ambition and desire for the throne in order to follow the plot through. Initially, the witches inform him that he ''shalt be King hereafter''. Macbeth adopts this prophecy as an objective, even calling it '' the deed'' as if it is something he must accomplish. His ambitious nature yearns to accelerate the process