Is a person held accountable if he kills someone who assaulted his حرم (violable private domain) or intruded into his home?

An aggressor against life, property, or honor is termed by scholars as a "ṣāʾil" (assailant). Repelling the assailant with whatever means necessary is permissible. The ruling on repelling an assailant varies depending on what he intends to transgress. If he intends to take property, repelling him is permissible but not obligatory. The same applies to defending oneself. However, when defending honor, the preponderant opinion is that repelling him is obligatory. The assailant must be repelled by the lightest means first, then progressively heavier means. If he cannot be repelled except by killing him, then killing him is permissible, and there is no sin upon the killer.