Little is specified about Garrett's early life, other than that he dropped out of school while in the sixth grade. How he received his murderous tendencies in the first place is also unknown. In his adult years, he married a woman named Helen, who became bald following a surgery for a brain tumor. He treated his wife with respect and their marriage seemed to be an averagely happy one. However, Garrett secretly began moonlighting as a serial killer, murdering young, short-haired, blonde women by stabbing them directly in the heart with an icepick, which was left there. After killing 25 victims this way, all within a span of two years, Garrett was finally apprehended by authorities. Pitiful for what he did, he showed police where he buried the victims and confessed to his actions. Garrett was eventually sentenced to death, scheduled to be executed by a firing squad (at his own request), and received daily visits from Helen, who was the only one who continuously supported him despite what he did. In prison, he began receiving at least two letters from a mysterious "fan". On May 25, 2008, an inmate attempted to shank him; a similar incident with a second inmate followed in November 15, 2010. In both shankings, Garrett was able to gain the upper hand and kill his assailants with their own knives.
Finally, on April 29, 2012, Garrett's execution proceeded just as planned. Minutes later, Dylan Kohler kills his first victim in the same style as Garrett's M.O. Throughout the episode, it is assumed by the BAU that Kohler, who was copying Garrett's murders, was the fan who sent the letters. By the end of the episode, it is implied that Helen might have written the letters sent to him.
Garrett targeted high-risk victims, such as prostitutes, drug addicts, and runaways, all of whom were young, short-haired, blonde women. He would break into their homes, ambush his victims, and tie them to their bed frames with duct tape. Garrett then killed them by a single stab with an icepick directed at the heart. Reid mentions that he showed the police where he buried two of his victims, suggesting that he tried to dispose of at least some of them. When he killed his assailants in prison, he would gain the upper hand on them during their attempts on his life and fatally stab them with their own shivs.
Garrett wasn't directly profiled by the BAU, as they were more focused on Kohler. However, the team's way of describing him makes him sound like a disorganized killer since he targeted high-risk victims and left mountains of evidence behind. His motivation is unspecified, although there were no mentions of him raping any of his victims, suggesting that he may have been driven by something other than sex. Also, because he showed pity during his arrest and confession, plus his good relationship with his wife, it may be possible that at least some of his victims were killed out of compulsion.
- Unspecified dates from 2003 to 2005:
- Linda Morton
- Ginger Palmon
- C. Breeka (full first name unrevealed)
- Kate Zondona
- Johnson (first name unrevealed)
- Nineteen other unnamed women
- May 25, 2008: Unnamed inmate (stabbed him in self-defense with his own shiv when he attempted to shank him)
- November 15, 2010: Unnamed inmate (killed in the same manner as the previous victim)
- Garrett bears some similarities to Cortland Bryce Ryan, a.k.a. The Angel Maker. Both targeted women, attacked them in their homes, used a sharp instrument in his killings (Garrett used icepicks to kill his, Ryan stabbed his with a screwdriver post-mortem), and eventually had someone commit a series of copycat killings.