Capital punishment cannot be justified.
The act of taking someone's life as a punishment is cruel, hypocritical, devoid of sense and totally immoral.
There are too many cases of the wrong person being convicted and there are too many cases, such as Bruce Ward's, where mental health assistance is required.
Don't support this madness. Talk about it, educate people about it. No country is civilised if it institutionally supports and perpetrates murder.
You can read about Bruce Ward here: