The rate of people shot by police in the US is 0.34 per 100k of its population. Who needs capital punishment when you shoot people your police doesn't like even before they have been found guilty?
And your anecdotal evidence is not really valuable in the discussion at hand. Somebody else can say the opposite, I for example live in a country where crime is treated differently and we have less violent crime. You can leave your doors unlocked in a major city, despite living in a red light district with its own share of homeless, drug addicts and mentally ill.