who was responsible for duncan's death, lady macbeth or macbeth?

This is a pretty common question about the play. I suppose, in the end, the final responsibility lies with Macbeth. It is Macbeth who salivates over the witches' suggestions and it is Macbeth who says ,“I am in blood stepped in so far that should I wade no more, Returning were as tedious as go o'er." L. Macbeth certainly plays her part. She prays on Macbeth's many insecurities, his "manhood" in particular. Although her ambition is great she cannot force Macbeth to kill everyone in sight. By the end of the play Macbeth is not even telling L. Macbeth who he is killing, "be innocent of the knowledge dearest chuck....". I think that much of what Macbeth does is because of obsession with ambition rather than simply ambition. In the end the fault must lie with him.