1. A person commits the offense of trespass in the first degree if he or she knowingly enters unlawfully or knowingly remains unlawfully in a building or inhabitable structure or upon real property.
2. A person does not commit the offense of trespass in the first degree by entering or remaining upon real property unless the real property is fenced or otherwise enclosed in a manner designed to exclude intruders or as to which notice against trespass is given by:
(1) Actual communication to the actor; or
(2) Posting in a manner reasonably likely to come to the attention of intruders.
3. The offense of trespass in the first degree is a class B misdemeanor, unless the victim is intentionally targeted as a law enforcement officer, as defined in section 556.061, or the victim is targeted because he or she is a relative within the second degree of consanguinity or affinity to a law enforcement officer, in which case it is a class A misdemeanor. If the building or real property is part of a nuclear power plant, the offense of trespass in the first degree is a class E felony.