Not much is revealed about Scott's early days, other than that he appeared to have done military service at some point. In the 1980s, he was an alarm installer in Philadelphia who moonlighted as a fetish burglar, frequently breaking into peoples' homes at night and stealing female underwear. He was considered a suspect for being the Keystone Killer, even being interviewed by profiler Max Ryan, who dismissed him from the investigation. At some point, he worked with Walter Kern, the real Keystone Killer. In 1988, the year Kern stopped killing due to being injured in a car accident, Scott killed a man during a botched routine break-in and was arrested and sentenced to jail.
In 2006, when Walter resumed killing, Scott was released on parole. In one of Kern's word-search puzzles, the word "NIBRAHS", "S. Harbin" backwards, was found. That, coupled with the fact that Scott has already violated his parole, leads the BAU to consider him a suspect, despite Ryan's strong objections, and raid his home along with a SWAT team. While searching through his home, they discover that Scott has abducted a woman, presumably with the intention to rape her, and arrest him. Outside his home, another letter from Kern is found, clearing Scott from any suspicions of being the Keystone Killer.
Since Scott only killed one person, the term "M.O." is misused. He killed this victim, a man, by stabbing him to death, most likely with a knife, when a break-in went wrong. How he managed to abduct the woman is unknown, but when he hid her, Scott wrapped her in plastic sheets and stored her under his own bed.
No official profile of Harbin was made by the BAU, since they were more focused on Kern.
- Unspecified dates:
- 1988: Unnamed man (stabbed)
- 2006: Unnamed woman (abducted; was rescued on February 26)