In State v. Nelson, 214 Ariz. 196,1, 150 P.3d 769, 769 (App. 2007), the defendant and a friend decided to assault the victim at a party because they were "tired of him pushing everybody around." 214 Ariz. 196,3, 150 P.3d at 770. The defendant punched the victim in the temple, knocking him unconscious, then hit him in the face and head about twenty more times, finishing with a blow to the chest. Id. His friend then "'chin-checked'" the victim three to five times. Id. The victim died later that morning from blunt force injuries to the head and chest. Id.4. The defendant was charged with one count of second-degree murder, and the trial court gave the jury an accomplice liability instruction because it was uncertain who actually had killed the victim. Id.5. The defendant ultimately was convicted of negligent homicide. Id.6. The Court concluded that, under these circumstances, the defendant could be convicted as an accomplice to an offense "with a culpable mental state of criminal negligence." Id.19.