Who is under suspicion for Duncan's murder?

Answer 1

Well, they didn't follow very good police procedure. On discovering the murder, Macduff called the others into Duncan's room. There they found Duncan stabbed to death, and a lot of blood about. His grooms, or bodyguards, had blood on their daggers and blood smeared on their faces. Macbeth, seeing this, and without any further investigation, killed them. When he was asked why he did that he answered that he was so angered by their apparent guilt that he could not hold himself back. Only later does the nagging question of motive come up. In Act II Scene 4 Ross and Macduff have the following conversation: Ross says, "Is it known who did this more than bloody deed?" and Macduff answers "Those who Macbeth hath slain." Ross then asks, "What good could they pretend?", meaning "what good could it do them?" Macduff answers, "They were suborned", which is to say, bribed. and anticipating Ross's next question, he says that since Malcolm and Donalbain have fled the scene, they are suspected of bribing the bodyguards. The logic of all this is highly suspect, but people in general are very poor at applying logic to questions of guilt and innocence. Only after the passage of time does this picture start to appear fishy to the people in Scotland, who realize that if Malcolm and Donalbain committed the murder, it did them no good whatsoever, but seems to have benefited Macbeth immensely. In particular, Lennox expresses this doubt about the all-too-quick resolution of the murder in Act III Scene 6, and hints that he now suspects Macbeth of the murder.

Answer 2

On the face of it, they have the best motive, being nearest in kin. Malcolm had already been singled out as the heir apparent. After they do a bunk, they are even more strongly suspected, as this is taken as evidence of guilt.

Answer 3

Suspicion falls on Malcolm and Donalbain, who appeared to have the best motive for the murder.