Marvin Barlow is a dangerous fugitive who spent over a decade on the FBI's Ten Most Wanted List.
Barlow had criminal connections of some sort to Max Keenan. One night, he snuck into the room of Max's daughter and stole her ring as proof that he could kill the girl at any time he wanted if Max didn't do as he said. As a result of Barlow's threats, Max and his wife abandoned their children and disappeared.
Barlow ended up on the FBI's Ten Most Wanted List at some point, but disappeared around 2003. At some point after his disappearance, Barlow died of unknown causes and was buried in Ohio. The authorities remained unaware of Barlow's death and he remained on the Ten Most Wanted List. After learning of Barlow's disappearance, Max was able to resurface, but always worried that Barlow would return and make good on his threats.
In 2015, Max somehow learned of Barlow's death and the location of his grave and dug up his body. Max was arrested for grave robbing, but was able to confirm that it was in fact Barlow and that he could finally stop looking over his shoulder for the man. The FBI finally learned of Barlow's death thanks to Max and Seeley Booth got the grave robbing charges dropped, at least in part because Max led them to Barlow. Max later robbed the coroner's office evidence locker and retrieved his daughter's ring before explaining Barlow's role in his disappearance.
- The Putter in the Rough (mentioned only)