(a) A person shall not be relieved of criminal liability for conduct because he engages in such conduct under a mistaken belief of fact, unless: (1) Such factual mistake negates the mental state required for the commission of an offense; or (2) the statute defining the offense or a statute related thereto expressly provides that such factual mistake constitutes a defense or exemption; or (3) such factual mistake is of a kind that supports a defense of justification.
(b) A person shall not be relieved of criminal liability for conduct because he engages in such conduct under a mistaken belief that it does not, as a matter of law, constitute an offense, unless (1) the law provides that the state of mind established by such mistaken belief constitutes a defense, or unless (2) such mistaken belief is founded upon an official statement of law contained in a statute or other enactment, an administrative order or grant of permission, a judicial decision of a state or federal court, or an interpretation of the statute or law relating to the offense, officially made or issued by a public servant, agency or body legally charged or empowered with the responsibility or privilege of administering, enforcing or interpreting such statute or law.