Colonel Henry Douglas serves at the Military Police headquarters in Central City and is tasked with arresting 2nd Lt. Maria Ross for the murder of Brigadier General Maes Hughes.
In the 2009 adaptation, there's an exclusive scene where Douglas interrogates Ross, showing her the bullet that killed Hughes. He reveals it matches the type she uses and questions her about a recent ammo requisition form. Ross explains she fired a bullet while protecting Alphonse at Laboratory 5 but finds it impossible to prove since the facility is now rubble with no witnesses.
Douglas also mentions eyewitnesses who saw Ross leaving the scene of Hughes' murder. Ross claims she was off-duty visiting her parents, but their testimony isn't considered credible for an alibi.
Douglas reappears after Colonel Roy Mustang seemingly burns Ross to an ashy skeleton, admonishing Mustang for letting personal issues lead him to such extremes. He notes that the excessive damage makes it impossible to confirm the corpse's identity.
His last appearance is in Chapter 35 when Roy and Lt. Hawkeye attempt to confuse the Military Police about Scar's whereabouts to help Edward and Alphonse Elric lure out the Homunculi.
Douglas's fate remains unknown, but it's possible he was arrested as a conspirator.
