1. A person is criminally responsible for the conduct of another when:
(1) The statute defining the offense makes him or her so responsible; or
(2) Either before or during the commission of an offense with the purpose of promoting the commission of an offense, he or she aids or agrees to aid or attempts to aid such other person in planning, committing or attempting to commit the offense.
2. However, a person is not so responsible if:
(1) He or she is the victim of the offense committed or attempted;
(2) The offense is so defined that his or her conduct was necessarily incident to the commission or attempt to commit the offense. If his or her conduct constitutes a related but separate offense, he or she is criminally responsible for that offense but not for the conduct or offense committed or attempted by the other person;
(3) Before the commission of the offense such person abandons his or her purpose and gives timely warning to law enforcement authorities or otherwise makes proper effort to prevent the commission of the offense.
3. The defense provided by subdivision (3) of subsection 2 of this section is an affirmative defense.