Which is always true, at least in the US. The police are allowed to lie to you during questioning. They are allowed to claim they have evidence that they do not have. No amount of lying on their part will invalidate any "confession" they obtain from you. But if you even inadvertently tell the police something that is untrue, you can end up in prison for that, even if you committed no other crime. NEVER talk to the police, if there is any chance they suspect you are involved with a crime.