Iowa Code § 703.1: Aiding and abetting.

All persons concerned in the commission of a public offense, whether they directly commit the act constituting the offense or aid and abet its commission, shall be charged, tried and punished as principals. The guilt of a person who aids and abets the commission of a crime must be determined upon the facts which show the part the person had in it, and does not depend upon the degree of another person’s guilt.