How was king Hamlet murdered what made it especially horrible?

In William Shakespeare's play "Hamlet," King Hamlet is murdered by his brother Claudius. Claudius pours poison into the king's ear while he sleeps in the orchard. This method of murder is particularly gruesome and shocking because it involves a close and intimate act of betrayal. The poison seeps into the king's ear, corrupting and destroying him from within. The fact that Claudius uses such a personal and underhanded means to kill his brother adds to the horror and treachery of the act.