No, you absolutely do not support our legal system. You support an imagined caricatur of it more suited for a dceveloping world or an authoritarian state. The existance of less than moral people has little to do with providing a very careful process before we allow the state to kill them. Your sense of victimhood is palpable, and overblown. This system, which you so decry for supposedly providing more rights to criminals than you, has now resulted in a country with the highest percentage of our population in jail in the world. Higher than the Soviet gulag period even. There are lots and lots of things that I don't want to pay taxes to support, legal due process is not one I begrudge the government paying for.
You so easily conflate anger at the person who did this crime with justification for removing core principles of our legal system. Fine, but recognize it as an emotional response to tragedy, not a reasonable policy proposal. And I agree, his death at the hands of the officers was justified: he shot, the returned fire, he was wounded and died. Justified. How in the world is this relevant to the belief that we should remove due process for death penalty cases?