Even the most brutal punishments throughout history don't really do anything other than to make the victims feel more better. I guess that's the point but I would rather look for solutions that prevent heinous crimes....like locking up anyone that acts or dresses weird, that should prevent quite a bit of crime.

...or we need to offer free mental health and enforce mental health services to anyone that even so much as slack jaws or stares at someone for too long.
But the real problem is that capital punishment doesn't even deter murders, never has.