LEV500 … the law of the rodef, the "pursuer"… states that if A is pursuing B to kill him, either directly or indirectly, anyone may save B even at the cost of A's life. This is inferred from the biblical law that a betrothed woman may be saved from rape at the cost of the assailant's life [this verse, Sanhedrin 73a]. The traditional capital charge with its formal court proceedings applied to acts that have already been committed; when the person himself had committed the murder and only when a human life had been taken. By contrast, the rule of the rodef applies to individuals before they have committed the crime and are only threatening. In other words, we are dealing here with prevention rather than punishment. The law of the rodef applies to crimes that are indirectly caused, even if the action is directed only against the property of the victim ... This kind of sentence does not depend upon properly constituted courts and formal rules of procedure, but any person who is witness to such a pursuit is obligated to take action.