Little is known about Coleman's personal life, other than he was once a Texas Ranger alongside Mateo Cruz, with whom he was acquainted with. In 2013, he was appointed as the new Sheriff of Silverton, Texas, replacing the old one, who (unbeknown to him) was murdered via an elaborate conspiracy by a ring of corrupt Deputies that was led by Owen McGregor. Because he was new to the job, the corrupt Deputies became threatened by his presence and formulated a large scheme to orchestrate his death, which started in 2013 with the murders of several prostitutes.
During the following year, Coleman uses his ties with Cruz to summon the BAU after observing their 2012 case-file on John Myers, a.k.a. "The Silencer". He assists the BAU in their investigation, and finally, the team deduces a suspect, a Christian preacher named Justin Mills, but they later find he is innocent because of his connection with the victims and that someone else is framing him. While preparing to confront Mills at a Spanish diner, Coleman is suddenly shot by McGregor, which prompts a shootout between Deputies and Mills, leaving several, including Reid, injured. As Blake and JJ try to drag Coleman to safety, McGregor shoots him again, hitting him in the forehead and instantly killing him.
In the aftermath of his death, the BAU deduce the true nature of the killings and go after the corrupt Deputies. Eventually, they shoot and kill several of them, including McGregor, avenging Coleman's death. By the end of the episode, Texas Rangers take over the investigation and arrest any remaining corrupt Deputies.
- Coleman has some similarities to Eva Ruiz, who appeared in the Season Five episode A Rite of Passage. Both were Texas Sheriffs who held their positions for less than a year and tracked the prominent cases, which motivated the killers to specifically target them and eventually become successful in their pursuits.