It is generally recognized by criminologists and psychiatrists that murder and other crimes punishable by death are almost never prevented by the apprehension of the punishment, for several reasons. First, crimes of passion do not get prevented by Reason. Second, the court system allows for plea bargains that preclude the death penalty (“take the death penalty off the table”). Thirdly, the long delay between conviction/sentencing and execution removes the cause/effect equation from the accused’s mind. Fourthly, the Constitutional language “cruel and unusual punishment” prevents any innovations, by definition, from being introduced. So, for these reasons, it is impossible to “create a method” to improve capital punishment. The only hope would be to replace capital punishment with some other onerous punishment “not unusual”, such as solitary confinement without visitor, TV, telephone, etc. privileges. Many science fiction and Utopian writers have suggested severely tranquilizing these prisoners, putting them in a state of suspended animation, where they could be alive and even aware but unable to move or respond in any way, but those are just fictional speculations, sure to be challenged in court. The place to spend social resources, research, etc. is in the area of how to prevent serious crime—some method of forestalling violent behavior before the criminal resorts to it. But that, too, is science fiction.