(a) A person is criminally responsible for the conduct of another when:

    (1)    The ordinance defining the offense makes him so responsible; or

    (2)    Either before or during the commission of an offense with the purpose of promoting the commission of an offense, he aids or agrees to aid or attempts to aid such other person in planning, committing or attempting to commit the offense.

    (b) However, a person is not so responsible if:

    (1)    He is the victim of the offense committed or attempted;

    (2)    The offense is so defined that his conduct was necessarily incident to the commission or attempt to commit the offense. If his conduct constitutes a related but separate offense, he 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 he abandons his purpose and gives timely warning to law enforcement authorities or otherwise makes proper effort to prevent the commission of the offense.

    (c) The defense provided by subparagraph (b)(3) of this section is an affirmative defense.

(Code 1964, § 7.575)

     State law reference(s)--Similar provisions, RSMo. § 562.041.