I didn't see him stopping any US citizens or asking anyone for papers.
Illegal drugs are... well... Illegal, but I know how those legal/illegal things confuse you. At no time did I see him shoot or threaten to shoot any illegal drug users.
I am guessing the state of Arizona has given him the right to do what he was doing. I am sure if they had even the slightest reason to put him in jail he would be arrested.
Yup, he was judge, jury and exacutioner. There were innocent bodies everywhere!!! (that's me being sarcastic in case you didn't get it)
Funny how you choose to forget certain parts of the story... seems to me I remember the reporter saying that the suspects were held until local LEO arrived.
Edit: By the way I am still waiting