Iowa Code § 703.2: Joint criminal conduct.

When two or more persons, acting in concert, knowingly participate in a public offense, each is responsible for the acts of the other done in furtherance of the commission of the offense or escape therefrom, and each person’s guilt will be the same as that of the person so acting, unless the act was one which the person could not reasonably expect to be done in the furtherance of the commission of the offense.