The Breakthrough ending explained: Is the killer revealed? Details explored 

Netflix's The Breakthrough is based on the infamous and real-life double homicide case, where eight-year-old Mohammad Amouri and fifty-six-year-old Anna-Lena Svensson were stabbed to death in broad daylight in 2004 in Linköping, Sweden.

The miniseries was released on January 7, 2025, and is an investigation into this cold case from sixteen years ago, which was finally solved in 2020 through DNA profiling and genealogy mapping.

The show follows Detective John Sundin, who becomes obsessed with this case for over sixteen years and finally decides to take a drastic step in 2020. In the finale, the killer is finally revealed after sixteen long years as journalist Stina's cousin David Nilsson.

Determined to solve the case, John contacted genealogist Per Skogkvist after sixteen years and asked his help to crack the case with all the evidence and data he had collected over the years about the case. And this move was a jackpot for John, as Per's meeting with journalist Stina Eriksson helped them crack the case.

More about The Breakthrough and how John and Per found the killer in our story.

Disclaimer: This article contains spoilers for The Breakthrough finale. Reader discretion is advised.

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Who is Stina Eriksson in The Breakthrough? How did she become the key for Per to find the killer?

Stina is an opportunistic journalist in The Breakthrough who sees this whirlwind case as an opportunity for an interesting scoop. She followed this case closely, interviewed Prime Detective John for this case, and published her unofficial conversations with him as official press releases.

When she discovered that John had contacted Per for genealogy mapping to find the killer, she saw this as a chance and interviewed Per about the process he was about to carry out.

Per demonstrates his techniques practically by taking Stina’s oral swab sample and explaining how this DNA sample can create her whole family tree, which could provide many answers about her ancestry. But little did he know that this chance demo would be the key to solving this case, as Francy takes the results of the oral swabs (including Stina's) to Per, which reveals that the killer is related to the journalist.

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Stina's cousin, David Nilsson, was revealed as the killer in The Breakthrough

While going through the oral swabs bought by Francy, Per discovers that Stina's results link her to two men (who are her cousins), who are already registered in their directory. The two men were identified as David and Stefan. Upon further investigation, John narrows down David as their prime suspect because he fits the description of the perpetrator.

They reached David's house to arrest him, and after some further tests, it was revealed that he was the killer in The Breakthrough. Moreover, David admitted to his crimes without any fight.

Upon further questioning, it was revealed that David was a loner and a depressed person with no friends or family. His parents had died, which made him into a loner. He said the 'voices in his head' told him to commit those murders, which would give him peace. This clearly shows that his mental health was disturbed and he needed help.

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