Ricardo gives a nod to Matt, the only American among/of the police officers, who takes out his gun and begins walking up toward the house.

Is there any difference between using "among" and "of" in the above sentence?


"Among" is natural and usual in this exact structure. "Of" is correct enough, but you usually see it used differently, as "the only one of the police officers who is an American". "The only American of the police officers" calls attention to itself and is therefore inferior in fiction writing.