(1) It is a defense to a charge of conspiracy that the actor, after conspiring to commit a crime, thwarted commission of the crime which was the object of the conspiracy, under circumstances manifesting a complete and voluntary renunciation of the criminal purpose of the actor. Renunciation by one conspirator does not, however, affect the liability of another conspirator who does not join in the renunciation of the conspiratorial objective.
(2) The defense of renunciation is an affirmative defense.