(1) Whoever in committing an act is mistaken about the existence
of facts which are part of the statutorily defined
constituent elements of a crime does not act intentionally. The
possibility of imposing criminal punishment for negligent conduct
remains unaffected.
(2) Whoever in committing an act mistakenly assumes the existence
of circumstances which would form part of the statutorily defined
constitutent elements of a lesser offense can only be punished
for intentional conduct in accordance with the statute defining
the lesser offense.