The default mode of execution should be whatever method the executee used on his victim. If that was very painful, we might allow him to request a different form of execution, at the discretion of the judge and with the concurrence of the victim’s family.
I completely agree with this. I can't imagine a better deterrent, unless it's an even more painful and grisly method. A swim in a piranha tank, for example, or an acid bath.
Beating to death with a blunt object should be on the list