Dexter: Original Sin Reveals Main Killer’s Identity (And Fans Are Stunned)

Spoiler alert for Dexter: Original Sin episode seven! Dexter: Original Sin has finally revealed who the big bad of the show is and it’s pretty shocking. Dexter is one of the biggest television franchises out there having started its award-winning run back in 2006. The original show ran for eight seasons, concluding in 2013 with a controversial and unsatisfying ending for fans. However, it was left open-ended so that Showtime could pick it back up later if they really wanted to. Despite kicking around ideas almost immediately after it ended, it would take nearly a decade before Dexter would grace TV screens once more.

In 2021, Michael C. Hall returned as Dexter Morgan in a sequel mini-series called Dexter: New Blood, which raked in incredibly viewership. Unfortunately for Showtime, the record breaking viewership concluded very quickly as New Blood was only intended to exist for a single season. With Dexter getting killed off at the end, the network looked to other ways to keep the series alive in some capacity. That spawned Dexter: Original Sin, a prequel series that chronicles Dexter’s first kill and his early days as an aspiring serial killer. So far, the show’s been a hit with fans and allowed Showtime the commercial success it desires while also setting up a sequel series known as Dexter: Resurrection which premieres this summer and began shooting earlier this month.

However, Showtime has to wrap up the first season of the prequel series and is in the final stretches of Dexter: Original Sin. After a short hiatus for Dexter: Original Sin, the show has returned with some stunning surprises. Episode seven, titled The Big Bad Body Problem, sees Dexter dealing with the body of his third victim, which inaugurated him as a serial killer, after his dumping ground was discovered by police. As this is happening, he also begins to investigate a new clue from the child kidnapper/killer haunting Miami Metro and its police captain, Aaron Spencer. In typical Dexter fashion, he is the first one to figure out the true identity of this person and it sends him spiraling.

Who Is The Killer in Dexter: Original Sin?

At the end of episode seven of Dexter: Original Sin, Dexter begins to put the pieces together around the identity of the big bad. Earlier in the episode, Spencer’s kidnapped child, Nicky, sharpens an object and uses it to cut the kidnapper’s hand. The kidnapper then severs one of Nicky’s fingers and sends it in a box to Miami Metro, leaving Spencer devastated. While helping analyze the finger, Dexter notices a blood drop on the outside of the box and believes it doesn’t belong to the finger. He eventually deduces it likely belongs to the kidnapper.

Spencer then thanks Dexter for his work and while talking to him, mistakenly reveals a cut on his hand similar to the one we saw on the kidnapper. Although Dexter doesn’t have the full picture, it’s enough for him to become suspicious that Aaron Spencer is the killer. We then see Spencer buying the same frozen lunches that the killer has been buying for his victims before noting to the cashier that his “son loves them.” With that said, it’s pretty obvious that Spencer is indeed this season’s big bad. Why is he kidnapping and torturing his own son? Why did he kill Jimmy Powel? We don’t really know.

His overall motive is pretty mysterious right now, though Spencer has been one of the suspects among fans for some time now. But this likely partially explains how Captain Matthews from the original Dexter series will be introduced. Spencer will likely be defeated at the end of Original Sin season one and then Miami Metro will need a new captain, making way for Matthews to make his debut. After all, it’s clear that Matthews and Dexter’s father had a good relationship, so he will need to be introduced well before Harry is killed off.

Dexter: Original Sin Confirms Dexter Was Not Miami Metro’s First (Or Only) Killer

Perhaps the biggest twist of Dexter: Original Sin so far is that Dexter was not the first killer within Miami Metro. Spencer was a dark force within the Homicide department and at an even larger level given he was the Captain. This is notable too because when Doakes is suspected of being the Bay Harbor Butcher, everyone in the department is in shock of how this could happen. This may suggest that the truth about Spencer never gets revealed to the public or the police station given it’s never addressed in the original series.

There’s also a sense of irony to it all as Patrick Dempsey also played a serial killer that was part of law enforcement in Thanksgiving. Nevertheless, it seems like Dempsey probably won’t be returning for season two of Dexter: Original Sin, unless Dexter finds a way to get him locked up or running for the hills, never to be seen again.