[0.E.O]

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).

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.

[butterdezillion]

The dart is made of a substance that melts when it penetrates the skin.

What do you know about potassium chloride?