(1) A person shall be guilty of an attempt to commit a crime if he or she:

(a) Intentionally engages in conduct which would constitute the crime if the attendant circumstances were as he or she believes them to be; or

(b) Intentionally engages in conduct which, under the circumstances as he or she believes them to be, constitutes a substantial step in a course of conduct intended to culminate in his or her commission of the crime.

(2) When causing a particular result is an element of the crime, a person shall be guilty of an attempt to commit the crime if, acting with the state of mind required to establish liability with respect to the attendant circumstances specified in the definition of the crime, he or she intentionally engages in conduct which is a substantial step in a course of conduct intended or known to cause such a result.

(3) Conduct shall not be considered a substantial step under this section unless it is strongly corroborative of the defendant’s criminal intent.

(4) Criminal attempt is:

(a) A Class II felony when the crime attempted is a Class IA, IB, IC, or ID felony;

(b) A Class IIA felony when the crime attempted is a Class II felony;

(c) A Class IIIA felony when the crime attempted is a Class IIA felony;

(d) A Class IV felony when the crime attempted is a Class III or IIIA felony;

(e) A Class I misdemeanor when the crime attempted is a Class IV felony;

(f) A Class II misdemeanor when the crime attempted is a Class I misdemeanor; and

(g) A Class III misdemeanor when the crime attempted is a Class II misdemeanor.