Marco Diaz

Marco Diaz is a sheriff's detective in the Florida Keys and a close friend of the Rayburn family, especially John. He's steady, well-liked, good at his job, and trusted by the people around him — the kind of cop who knows everyone in town and is genuinely fond of them, before the family's troubles start pulling at that trust.

Enrique Murciano plays Marco as plainly decent, which is rarer and harder than it sounds on a show built around people who lie for a living. He's the audience's measure of normalcy, a friend whose warmth toward the Rayburns makes it sting more when their secrets edge into his professional life.