After twenty years of hard work, Leo, a hardcore Libertarian, founded the Liberty Ranch, a small, self-sustaining community located in La Plata County, Colorado. At some point after the ranch's creation in 1980, a young woman, who was five months pregnant, joined the community, giving birth to a son she named Charles Mulgrew. Charles was unusually intelligent (possibly possessing an eidetic memory) and had a defiant attitude, much to Leo's annoyance. When Charles was seventeen, a group of young girls came to Leo and told him Charles had molested them, prompting Leo into kicking him out of the ranch, sending him and his mother fleeing to Kentucky. In 2000, Charles (now going by "Benjamin Cyrus") returned, claiming his mother had died and that he had found God. Leo was usurped when Ben, claiming God had told him to take over the ranch, put a gun to his head and kicked him out. Ben then introduced religion to the ranch, transforming it into a cult that came to be known as the Separatarian Sect. Leo was eventually arrested, charged with tax evasion and assault (the latter for attacking four IRS agents with a baseball bat) and was sentenced to seventeen years in Deer Field Federal Prison.
In 2008, when a raid on Liberty Ranch (sparked by rumors of illegal weapons hoarding and sexual abuse) goes awry and Reid and Prentiss are taken captive, the BAU gets in touch with Leo in order to get information, arranging for him to be transported to La Plata County. Leo tells Morgan about Ben's past and how he took over, also claiming that he will do anything to help them "send that ungrateful son of a bitch straight to Hell". Leo ends up providing Morgan with an extensive map of the ranch.
- Four unnamed IRS agents (all assaulted)