If you just finished the finale of Apple TV+’s Presumed Innocent, your head is probably spinning. You spent weeks looking at Rusty Sabich—played with a sort of frantic, sweaty desperation by Jake Gyllenhaal—thinking he was the one who bludgeoned Carolyn Polhemus to death. Then, the rug gets pulled out. It wasn't Rusty. It wasn't even the creepy guy from the evidence files.
It was Margo.
Wait, let's get the names straight because the show changes things from the original Scott Turow novel and the 1990 Harrison Ford movie. In this 2024 reimagining, the daughter is named Jaden (played by Chase Sui Wonders), but fans of the book and the lore often go searching for the "why" behind the family betrayal. In the 2024 series, the shocker is that the daughter, Jaden, killed Carolyn. But if you are looking at the broader history of this story and the specific character dynamics, the question of why did Margo kill Abby—or why the daughter killed the mistress—is the heartbeat of the tragedy.
It wasn't about a simple grudge. It was about a family’s survival instinct gone completely off the rails.
The Breaking Point: Protecting the Nest
So, why did it happen? Why did a teenager commit such a brutal act?
In the context of the show’s massive finale, the "Margo" figure (Jaden) didn't go to Carolyn’s house to commit a pre-meditated murder. She went there for a confrontation. Imagine being a kid watching your mother, Barbara, wither away while your father carries on a public, humiliating affair with a colleague. You see the stress. You see the silent tears at the kitchen table.
Jaden (the "Margo" role) went to Carolyn’s house to tell her to stay away. She wanted to protect her mother's sanity. But Carolyn dropped a bombshell: she was pregnant with Rusty’s baby.
That was the catalyst.
In that moment, Carolyn wasn't just a mistress anymore. She was a permanent threat. She was someone who was going to tether Rusty to another life forever, effectively erasing Jaden’s own family. The fire poker was right there. It was a crime of passion, a momentary lapse in sanity driven by a fierce, almost primal need to keep her parents together.
The Difference Between the Book and the Screen
If you’re confused about the names, it’s because the Presumed Innocent universe has shifted over the decades. In the original 1987 novel by Scott Turow and the subsequent 1990 film, the killer is actually Barbara—the wife.
The 2024 series changed the killer to the daughter to up the stakes.
In the original version, Barbara (played by Bonnie Bedelia in the movie) kills Carolyn because she wants to "leave a calling card" for Rusty. She wanted him to know, with absolute certainty, that she knew what he had done. She cleaned the scene meticulously. She planted evidence. It was a cold, calculated move by a woman who had been pushed to the edge of a psychological cliff.
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The TV show writers clearly felt that in 2024, the "scorned wife" trope was a bit too predictable. By making the daughter the killer, they tapped into a different kind of horror: the idea that a parent’s sins are visited upon their children. Jaden killed Carolyn because she couldn't stand to see her family dissolve.
The Cover-Up: Rusty’s Fatal Mistake
The tragedy of why did Margo kill Abby (or Jaden kill Carolyn) is compounded by what happened after the blood was spilled. Rusty Sabich is a prosecutor. He knows how to read a crime scene. When he arrived at Carolyn’s house and found her dead, he didn't call the police.
He thought his wife did it.
Rusty spent the entire trial—and the entire series—not just defending himself, but "cleaning up" the scene because he was certain Barbara was the murderer. He tied Carolyn up to make it look like a fetishistic killing linked to a previous case (Liam Reynolds). He contaminated the evidence.
The irony is sickening. Rusty was trying to protect his wife, while his daughter was the one sitting in the courtroom watching her father almost go to prison for a crime she committed.
Why the Ending is So Polarizing
People are genuinely angry about this ending. Why? Because it changes the moral DNA of the story. In the original version, Rusty and Barbara stay together in a sort of "mutually assured destruction" marriage. It’s dark. It’s gritty.
In the 2024 version, the reveal that the daughter did it makes Rusty look even more incompetent. He’s a world-class prosecutor who couldn't see the truth right in front of his face. He was so blinded by his own guilt and his assumptions about his wife that he missed the signs that his daughter was traumatized and unraveling.
Honestly, the "why" boils down to a single word: Obsession. Rusty was obsessed with Carolyn. Barbara was obsessed with maintaining her dignity. And Jaden was obsessed with saving a family that was already dead. It’s a cycle of toxic behavior where the youngest person in the room ends up paying the highest price.
Misconceptions About the Forensic Evidence
A lot of viewers wondered how a teenager could pull off such a brutal killing without leaving a trace. Here’s the thing: she did leave traces. But because Rusty got there first and "staged" the scene to look like a professional job, he inadvertently masked the amateur mistakes Jaden made.
- The DNA: Rusty’s skin cells were everywhere because he lived there, basically.
- The Weapon: The fire poker was a household object, not a premeditated murder tool.
- The Timing: Jaden slipped in and out while the house was empty, and since she wasn't a "usual suspect," the police didn't look at her phone pings or her timeline until it was far too late.
The prosecution was so focused on the "jilted lover" narrative that they never even considered the "traumatized child" angle. It’s a classic case of tunnel vision in the legal system.
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What This Means for Season 2
With a second season of Presumed Innocent confirmed, the fallout of this reveal is going to be massive. Even if the show moves to a new case (as an anthology), the ghost of this decision hangs over the franchise.
If you are looking for the psychological "why," you have to look at the garden scene. Jaden tells her father that she didn't want him to leave. She didn't want the baby to exist. She wanted things to go back to the way they were. It is a heartbreakingly childish motive for a very adult crime.
Key Takeaways for Fans of the Mystery
To truly understand the weight of the reveal, keep these points in mind:
- Check the Source: If you’re discussing "Margo" or "Abby," make sure you aren't mixing up character names from other thrillers like Gone Girl or the original Turow sequels. In the 2024 series, the names are Jaden and Carolyn.
- Watch the Parents: The show is less about the murder and more about the "silent" conversations between Rusty and Barbara. Their inability to be honest created the vacuum that Jaden filled with violence.
- Re-watch the Evidence Scenes: Knowing the killer is the daughter makes the early scenes where Rusty "cleans" the apartment ten times more intense. He’s literally burying the truth while trying to save a woman who didn't even do it.
If you want to dive deeper into the legal nuances of the show, research the Liam Reynolds subplot. It’s the key to understanding how Rusty thought he could get away with the cover-up by mimicking a past killer’s MO. Understanding that specific legal failure explains why the police were so easily led down the wrong path from day one.