In the Cunda Kammaraputta Sutta:
There is the case where a certain person, abandoning false speech, abstains from false speech. When he has been called to a town meeting, a group meeting, a gathering of his relatives, his guild, or of the royalty, if he is asked as a witness, 'Come & tell, good man, what you know': If he doesn't know, he says, 'I don't know.' If he does know, he says, 'I know.' If he hasn't seen, he says, 'I haven't seen.' If he has seen, he says, 'I have seen.' Thus he doesn't consciously tell a lie for his own sake, for the sake of another, or for the sake of any reward. Abandoning false speech, he abstains from false speech. He speaks the truth, holds to the truth, is firm, reliable, no deceiver of the world.
For example, a monk witnesses a murder and asks by a police for information. The monk knows his information/testimony will cause the murderer got murdered. Is giving this testimony break any vinaya rules or correspond to the rules?
As explained previously on another thread: Enlightened Lies - Can lying be the correct action in certain situations?
Skillful means can be used to deal with this situation or lying with the intention to save others. But the same thing can be true as well, for example, when someone is asked by the police, his intention is to tell the truth, it's not his decision to take the murderer life away. Is truth telling in this case is right or wrong and why?