Easy, how he/she/they tortured the animal, we would torture him/her/them in the same way. This is the best to do. How you killed someone, you will be killed the same way. Do not give any service order, do not put them in jail. It is useless. No one would scare such purnishment. And it would be just a waste of tax payer's money. The only way is to treat them the way they treat others.