Multiple news sources, including this piece, have stated that Zimmerman had attained the rank of “captain” in the neighborhood watch.
“Now, Zimmerman is wearing a gray prison jumpsuit instead of black robes, as he faces second-degree murder charges in the Feb. 26 shooting of Trayvon Martin, an unarmed black teenager who was walking home through the housing complex where Zimmerman served as a neighborhood-watch captain.”
I see. I don’t consider the rank of Captain of neighborhood watch as an official rank, therefor I don’t think he should be called Capt. Zimmerman.
Looks a bit silly IMO. But if you feel it is necessary then by all means go for it.