There’s a potassium chloride dart that can cause a heart attack within seconds, leaving nothing detectable in an autopsy so the only evidence left behind is a small red entry hole that’s sort of like a bug bite, which is what the victim would think had happened (in those last few seconds of life).
From what was in the autopsy report for Breitbart, the coroner did not check for an entry hole like that.
Aren't you forgetting one thing left behind? One piece of evidence like, I don't know, THE DART?????
Besides, a fatal dose of potassium chloride for someone like Arpiao would be about two teaspoons and would have to be administered into a vein for it to be effective.