Dexter: The distraction stories I referred to was the beheading cases Deb was working. Being confronted with the horror and monstrously vicious nature of the crimes and the inhuman brutality of the criminals culminated in her gunning down one of the perpetrators with no remorse (especially given that in an identical situation earlier in the season, her hesitation resulted in a hostage getting his throat cut and nearly dying and the killer escaping). Subsequently, she is punished unjustly for her actions. She and her fellow officers are subjected to criticism & blame by the general public and their superiors alike, and her immediate superior and protegee both betray her over that case. She also finds herself seeking and finding comfort in a relationship with a cop previously established to have questionable ethics and a dubious character, and thus not remotely the sort of person she would welcome into her life before this season. Likewise, to the best of her knowledge, she has lost a sister-in-law to a serial killer, whom the authorities are absolutely powerless to stop and who has gotten away scot-free. With all of this development, her subsequent confrontation with the horrors inflicted on the "barrel girls" leads to her decision in the finale to allow the cornered vigilante-revenge killers to escape. She has had the horror of cruel and senseless murders hammered home repeatedly all season and the "system" and her police job seem to be conspiring against her efforts to stop them. Her superiors are seen to demand instant results, while complaining about the cost and threatening to end the investigation, with miracle discoveries or progress at the last second barely keeping her case alive, and when she finally does stop the killers, her means and method are criticized and she is punished for her own superior's interference and equally importantly, betrayed by her subordinate. All of this explains why the woman who ardently pursued the Bay Harbor Butcher vigilante killer in season 2, and was not willing to accept the slightest justification for the killer despite the general belief that he was a man she knew and liked (Doakes), who has devoted her life to being a cop and followed the rules all the way, would be sympathetic to the mysterious killers she corners behind a curtain in the finale - they are at least achieving justice and stopping criminals with their method, while her path seems to constrain and inhibit her performance at every turn.

But little or none of the development of this arc is apparent until the last few episodes when she openly expresses her admiration to her brother and her partner for the vigilantes she theorizes are responsible for the disappearances of the suspects in her case. Without the Santa Muerte killings, the stakeout for the Fuentes Brothers and the drama with Laguerta and Mansone, we would not understand how and why she can continue a romantic relationship with a cop, who, if not guilty of murder, seems to at least be up to some highly suspicious activity, and of course, walk in on two killers in the midst of disposing of a body and allow them a head start to escape without trying to see their faces. Furthermore, there is something almost viciously vindictive in the method she chooses to provide that headstart - she leaves the room to call for back-up as per proper officer safety procedures, which is not only plausible deniability, but the sort she rub in the faces of the officious superiors should the escape of the killers ever be discovered. "See, I did it your way, and the killers escaped! And you can't even think about criticizing me because I followed YOUR beloved rules to the letter!" But with more F-bombs, Deb being Deb.