ending of Dexter: New Blood, Original Sin will explore the distant past of the serial killer's life. While the story of Dexter's early adulthood has mostly been left untold, other shows in the franchise have already revealed six of his earliest victims.

The timeline of Dexter: Original Sin places the prequel show in the early 1990s, and there are a few victims that Dexter, New Blood, and a forgotten web-series began to reveal from that time frame. While the exact dates of Dexter's kills aren't well-established, and there have been some minor retcons to his first kills, there are still six victims who could easily appear in Original Sin. There's no telling whether the show will actually include these characters or simply change them, but they're still worth learning about.

6 Nurse Mary

Dexter Season 1, Episode 3 - "Popping Cherry"

The first, and most important, of Dexter's kills that Dexter: Original Sin will likely depict is also his first ever kill. Nurse Mary was the first person Dexter ever killed, and the original series actually went into a good amount of detail about her. Mary was Harry Morgan's nurse when he was first hospitalized for heart disease, and Dexter's father quickly realized that she was poisoning him. Harry then learned that she had been giving him and other patients overdoses of morphine, and that she was a serial killer. To save his own life and her future patients, Harry told Dexter to stop her.

Since Mary was Dexter's first victim, his killing ritual was much sloppier and less refined. Like usual, Dexter covered Mary's apartment in plastic lining and ambushed her when she came home, but she was able to briefly stop him from injecting her with the tranquilizer. Dexter did eventually get her onto the table, and she told him that she wanted to take her victims' pain away. Dexter then killed Mary, and Harry lived for another year since he was no longer being given overdoses of morphine.

Of all six kills that fit Dexter: Original Sin's timeline, Nurse Mary is the most likely to be depicted on-screen, simply due to its importance. It wouldn't make much sense for a show depicting Dexter's origins to not include the first person he ever killed, and since Mary had such a prominent role in Dexter season 1, it wouldn't make much sense to change her story. Of course, Original Sin could also skip over Mary and pick up with Dexter's life after he killed her, but if it does show her death again, it could give some valuable new insights into Dexter's first victim.

5 Unnamed Second Victim

Dexter Season 8, Episode 2 - "Every Silver Lining..."

Unfortunately, almost nothing is known about Dexter's second victim. The only reason his second victim is known at all is that Dexter revealed both Nurse Mary, Dexter's first victim, and an unnamed drug dealer who was his third victim. While that leaves very little information about who Dexter's second victim was, there are some context clues that can help determine what happened in his second outing as a serial killer.

Dexter already showed that he was fairly unrefined in his first kill, Nurse Mary, and it's safe to assume that his second kill was similarly disorganized. He likely learned a few lessons from his first outing, like how to ambush people from behind, but he was more than likely still working out some kinks in his modus operandi. Additionally, since Harry mentioned that Dexter started displaying photos of his targets' victims during his third kill, that means he didn't have any photos on display for his second kill.

The possibilities are endless, which makes Dexter's second victim a prime candidate to be put into the spotlight in Original Sin.

Since there are so few defined details about Dexter's second kill, it seems extremely likely that Original Sin will examine it more closely than anything else in the franchise has. Dexter's second victim is essentially a blank canvas, and Original Sin can depict it in any way without contradicting established canon. The possibilities are endless, which makes Dexter's second victim a prime candidate to be put into the spotlight in Original Sin.

4 Unnamed Drug Dealer

Dexter Season 8, Episode 2 - "Every Silver Lining..."

There's a bit more information about Dexter's third victim than there is regarding his second kill, but not much. Thanks to the recordings of Harry's conversations with Evelyn Vogel in Dexter season 8, there are a few key details about Dexter's third kill. He was a drug dealer who robbed and killed two college students who had bought drugs from him. Harry also mentioned that Dexter's third kill was when he started displaying photos of victims in his kill room. Vogel hypothesized that Dexter was displaying a basic understanding of justice at that moment, and it helped convince Harry to keep training Dexter.

Similarly to Dexter's second victim, the unnamed drug dealer seems like a prime candidate to be shown on Original Sin. The previous shows haven't revealed much about the drug dealer, which opens quite a few possibilities for Original Sin to explore his death and make it unique. Additionally, the drug dealer presents an opportunity for the prequel series to dive into Dexter's practice of showcasing his targets' victims, which could be a very interesting way to explore his development as a serial killer and his internal sense of justice.

3 Juan Ryness

Dexter Season 2, Episode 10 - "There's Something About Harry"

Other than Nurse Mary, only one of Dexter's earliest victims was actually shown on-screen in Dexter. That was Juan Ryness, a pimp and drug dealer who was one of the last victims Dexter killed before Harry's suicide. Dexter was actually somewhat inconsistent with Juan, as he was originally described as just a pimp who was being let go because of a faulty warrant. In Dexter season 8, however, Harry told Evelyn Vogel that he walked in on Dexter killing a drug dealer who had also killed his partner on the police force.

Aside from the retcon, Juan Ryness actually plays a very important role in Harry and Dexter's relationship. Juan was the first person Harry actually saw Dexter kill, and he couldn't handle the sight of what his adoptive son had become. Harry puked when he saw the body, and as Captain Matthews explained, Harry killed himself by overdosing on his heart medication because he couldn't handle the guilt. Harry obviously died as a result of Juan's murder, but his reaction also haunted Dexter for a long time, and it was a big reason he let Miguel Prado learn so much about his Dark enger.

Since Juan Ryness' death had such far-reaching repercussions, there's a good chance he'll appear in Dexter: Original Sin. The prequel show seems to be focused more on Harry than the original series ever was, and such a critical moment in his relationship with Dexter likely means that Juan Ryness is the perfect victim to include. However, given how important Juan is to Harry's suicide, he likely won't be tackled until nearly the end of Original Sin, or at least closer to when Harry dies.

2 Robert Milson

Dexter: Early Cuts - "Dark Echo"

The two remaining victims who Dexter likely killed in the 1990s were both from the Showtime web-series Dexter: Early Cuts. That web-series depicted a handful of Dexter's kills prior to 2006, when Dexter began and when he first encountered the Ice Truck Killer, and only two of them happened in the 1990s. One of his victims at the time was Robert Milson, a criminology professor at Dexter's college. Early Cuts explained that Harry had been tracking Robert ever since he was 15, as Robert had been acquitted of a murder charge for strangling his girlfriend at the time.

Dexter began hunting Robert shortly after Harry's death, and he moved fairly quickly. He learned that Robert had killed seven young women who took his class over the years and dumped their bodies in the Everglades. Dexter ambushed Robert while he was grading papers and killed him in his office. He then dumped Robert's body in the Everglades, both because he didn't have access to his boat at the time and because Harry had taught him that bodies decay extremely quickly there.

As a free web-series, Early Cuts doesn't seem like an essential part of Dexter canon, and the prequel series could easily disregard it.

There's only a small chance that Dexter: Original Sin will include Robert Milson. The trailer for Original Sin showed Dexter in a cap and gown, and since the show will depict his first days working with Miami Metro as a blood spatter analyst, it seems like he's out of college. That would mean the show is set after Robert's death, but it could always be shown in a flashback, and Original Sin could simply change the chronology of Early Cuts. As a free web-series, Early Cuts doesn't seem like an essential part of Dexter canon, and the prequel series could easily disregard it.

1 Peter Thornton

Dexter: Early Cuts - "Dark Echo"

Dexter met one of his earliest rivals through Robert Milson in Early Cuts, and he could make the jump into Original Sin. Peter Thornton was Robert's teaching assistant, and when he stumbled into Robert's audience to help him with grading, he witnessed Dexter killing the professor. Peter then engaged Dexter in a game of cat and mouse by capturing another of his targets before Dexter could get to her. After Peter killed her, Dexter met up with him and refused to teach him the Code of Harry, even though he called Peter his "dark echo."

Dexter: Early Cuts is available to watch on YouTube.

After Dexter rejected him, Peter continued his killing spree by murdering a campus guard so that Dexter would find him. Since he had taken an innocent life, Dexter decided to kill his echo. He left a message for Peter, telling him to meet him in a warehouse, and after a brief struggle, Dexter had him on his table. Just before taking a circular saw to his neck, Dexter told Peter how he was honoring his father by killing other killers. Interestingly, Peter is technically one of the few characters who knew about Dexter's dark enger.

Interestingly, the biggest reason Peter Thornton may not be included in Original Sin isn't because he comes from Early Cuts, but because he would be redundant. The original Dexter show already explored the idea of Dexter having a protégé - twice, in fact. Dexter tried to teach both Miguel Prado and Lumen Pierce how to kill according to Harry's Code, and Peter's story would feel very similar to theirs. Dexter: Original Sin will probably try to find its own footing without rehashing the same storylines as the original Dexter, and Peter will likely be left on the cutting room floor.