Do you support the death penalty in America and why??

Do you support the death penalty in America and why??
I was just having this conversation with my dad before and he said he really disagrees with me. i was saying that by the government having a death penalty, they are giving off the message that it certain circumstances it is ok (and sometimes even right) to kill someone. once we start making exceptions to the "no killing" rule, the country really can turn into people taking matters into their own hands. in other words... if a man has a really good reason for killing someone, why shouldn't he think he's allowed to? the government does it? i feel like once we start drawing lines and saying that in "this" situation it's ok to kill, we are giving off a terrible message and one that leads people to believe that they can take matters into their own hands if they have a good reason. my dad disagrees. what do you think?.