What about the serial killers? The mass murderers? Do they deserve the same treatment as well? If they all use mental illness as the reason for their crime, it will be a shame to people who are truly suffering from it. Sometimes, a person who has done a terrible crime deserves to be sentenced to death. But as for alternative to death penalty ideas, the only thing I can think of is to have them experience what their victims experienced. For example, have a rapist be screwed over and over and over by a pig or a horse. Or starve them off. Lock them in a padded cell with a noise barrier while limiting their food and drink supplies.