Under what grounds can George Zimmerman of Florida be arrested?

Can he be detained for questioning?

If George Zimmerman isn't arrested or detained, then couldn't any person in Florida claim self-defense if the circumstances are right? Based on the facts of the case, what separates George Zimmerman from murdering Trayvon Martin and Zimmerman claiming self defense? His own statements? One eye-witness? Can they at least question him to get all of the facts straight?