A person is not guilty of an offense if his or her conduct is incited or induced by a public servant or his or her agent for the purpose of obtaining evidence for the prosecution of such person.

However, this section is inapplicable if a public servant or his or her agent merely affords to such person the opportunity or facility for committing an offense in furtherance of criminal purpose which such person has originated. Entrapment is an affirmative defense which must be proved by the defendant by a preponderance of the evidence.