"Who Killed Sara?" Season 3 Finally Gives an Answer to Its Biggest Question

At times, Mariana seems as if she's simply been corrupted by César and is only following his lead. However, the flashbacks tell a different story, as we see Mariana learn that Sara is carrying César's child. The pair then go on a walk where Mariana contemplates pushing Sara off a cliff before ultimately conspiring with Elroy to get rid of the girl. It is Mariana who suggests Sara try parasailing and Mariana who hands the knife to Elroy in the hopes he'll tamper with the harness.

Through flashbacks, we learn Elroy doesn't use the knife, but Mariana assumes he did. She then cleans up the scene of the crime while pretending to call an ambulance for Sara. In the present, Elroy confesses to Mariana that he did not kill Sara and that he wasn't able to go through with their plan. From her reaction, it's unclear if she thinks he's lying or is afraid he's telling the truth. After his confession, she murders him in his hospital bed, effectively silencing him forever. Despite having strong motives for being the killer, and a plan in place for the murder, Mariana did not kill Sara.

For the longest time, "Who Killed Sara?" certainly implies that César is the one that kills Sara. César's the one that talked Álex into taking the fall for the Lazcano family when Sara was first killed, and it is César's baby Sara was pregnant with at the time of her death. The only person César looks out for is himself. That's clear from how he treats his family and the women he sleeps with.

During season one, César tells the others he's not a killer, and by seasons two and three, we see his statement holds more truth than expected. While César has killed in the past, including the body buried in Álex's backyard, he doesn't do it just for fun, unlike his associate Sergio. He kills Abel Martinez, Sara's real father, because he tries to murder Sara. Although César may be a shady businessman and an even sh*ttier father, he's not the one who killed Sara.

The second season of "Who Killed Sara?" is a wild ride that ends with the realization that Marifer, one of Sara's best friends and Álex's confidante, may have been responsible for Sara's death. Much like Álex, Marifer is fueled by her need for revenge on the Lazcanos since she believes that they're the ones who killed her mother. To enact her revenge, she gets her sister Clara to become Chema's surrogate in the hopes of extorting information from Mariana.

All of Marifer's plans begin to unravel when Álex and Nicandro discover a hidden tape labeled "Abel" in Sara's room. The tape reveals that not only is Sara actually Álex and Marifer's half-sister, Marifer's father Abel is the one who killed her mother. As she leaves Álex's house, Marifer flashes back to the day Sara died and we see her frantically cutting the parachute's harness. So, did Marifer kill Sara? Everyone believes she did, including herself, but the final scene of "Who Killed Sara?" shifts the blame to someone else entirely.

When we spoke to Manolo Cardona back in April, he teased the arrival of "a very important character," and it seems the "Who Killed Sara?" star was talking about Nicandro. After we were led to believe he had died before the events of the show's first season, it was a surprise to see just how big of a role Rodolfo's former best friend plays in the mystery.

Nicandro spends most of the season in the background under the guise of just wanting closure with everyone from Sara and Álex to Marifer. However, his true motives are later revealed when we learn through a flashback that not only did Sara and Nicandro sell drugs together, but she also tried to kill him.

In the final moments of the second season finale, Nicandro is seen rummaging through a file cabinet before finding Sara's medical records. Her records indicate that she was the "first patient of the project." Nicandro then calls Dr. Alanis, the same doctor Álex visited to find out more about his sister's condition, and reveals that the doctor took a bribe from his father and that it's better everyone believes Marifer killed Sara. While we now know that Nicandro and Dr. Alanis are technically the ones behind Sara's death, we later find out that they weren't the ones who actually killed her.

Toward the end of the first season, Álex discovers Sara's notebook hidden away in a wall. Her writings and scribbles detail Sara's battle with depression and suicidal thoughts. Sara also stole a tape of Sergio murdering Flor, hiding it with her friend Marifer as insurance against any possible retaliation from César or Sergio. When Álex discovers Sara's journal, he calls Elisa to let her know they've been wrong about everything.

By the end of the second season, Álex learns that Sara had been diagnosed with schizophrenia, which she genetically inherited from her father Abel. Sara begins acting out upon learning that Abel is her birth father, and her relationships begin to implode with those around her. Shortly before her death, she's seen messing around with the knife on the boat but drops it before she can do anything. There's no denying that Marifer is the one who tampers with the parachute's harness, but the season two finale discloses that Sara was a part of a mysterious study at the Medusa Center led by Nicandro's father, Reinaldo.

In season three, we learn that Sara didn't actually die from the parachute accident as we were led to believe. Instead, she died by suicide after she stabbed herself with a knife at the Medusa Center after undergoing torturous treatment from Reinaldo in his attempts to cure schizophrenia. "You've lost what you most wanted," Sara tells Reinaldo in her final moments.