Question: If one drives his enemy into madness and then that mad person commits an evil act and kills himself, or any other crime, who should be held accountable for these sins on the Day of Judgment? Is it the mad person, or his enemy who drove him mad, or the one who worked magic on him? Which of the three bears the sin? Given that the madman’s enemy did not drive him mad himself, but hired a sorcerer to drive him mad.
Answer: Causing harm to others is forbidden; one who does so bears as much of sin as he has committed. It is also prohibited to hire a sorcerer to harm a person, and the work of that sorcerer is considered Kufr (disbelief), as Allaah says (what means)… read more here.