Tie a wire tightly around it, tie the wire to a rope and hang the sonofabitch
Now just a cotton pickin’ minit here. Let’s be fair. The punishment ought to fit the crime, and there are plenty of farm implements available for the purpose. They acted like animals, let them be gelded like horses or capons, and film it so they can be shown the video over and over while in prison, and put the video up on facebook.