Captain Miller relieved Corporal John Beecham of his duty after witnessing disturbing behavior when they were called to keep the peace during the Haymarket riots.
He is a guest-starring character portrayed by Eric Johnson.
In the first half of the 1880s, Captain Miller was the Head of the platoon where corporal John Beecham was enlisted into. Captain Miller described him as "disciplined, attentive to detail, efficient". However, Beecham attracted negative attention to himself during the Haymarket riots. On May 4, 1886, at Haymarket Square in Chicago, his platoon was called in to "keep the peace, but the violence got ugly. A bomb thrown amongst police, rioters shot and killed." During the retaliation, Captain Miller came across him sitting astride a dead striker, stabbing at the body with a knife, over and over. To make matters worse, Beecham was completely naked, covered in blood and sexually aroused as he defaced the corpse. He was sent to the St. Elizabeth's Hospital, informally known as Government Hospital for the Insane after being found unfit for service by the Regimental Surgeon. 
When detective sergeants Marcus and Lucius Isaacson went to North Dakota to investigate potential suspects following recent developments in their investigation, Captain Miller received their visit. In an Indian reservation, the captain told the two policemen about the circumstances he met John Beecham and how he shown to be mentally unstable during the suppression of the Haymarket riots. 
Appearance and Personality Edit
Captain Miller is an average good-looking man in his late thirties. With blond hair, sunburnt skin and blue eyes, Captain Miller wears his platoon's uniform. He is a man who is loyal to the uniform and to the cause in which he believes. Despite his military career, he admitted that he had never seen so much horror as the one perpetrated by John Beecham.
- Capain Miller: "You've come all this way to inquire about Corporal Beecham?"
- Lucius Isaacson: "You remember him?"
- Capain Miller: "Remember him? It's been ten years, and I can't get him out of my head."
- Capain Miller: " I've seen men driven to bloodlust out here in the West. Never in a place like Chicago and certainly not in the course of a labor riot."
- Capain Miller: "I mean, you must be half-crazy to do what he did that day. [...] I came across him sitting astride a dead striker. Young man body, really in a back alley. He was stabbing at the body with a knife, over and over. That wasn't the worst of it. He was naked from head to foot, drenched in blood. Down there, between his legs, he was stiff as a flagpole."
- Ep. 8: Psychopathia Sexualis