Who is the killer in Netflix's Adolescence? Did Jamie kill the girl?

19 March 2025, 11:01 | Updated: 19 March 2025, 11:37

Who is the killer in Adolescence? Did Jamie Kill Katie? Picture: Netflix

By Katie Louise Smith

Did Jamie kill Katie in Adolescence? Series co-creators explain why it was important that they revealed the murderer early in the series.

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Netflix's latest critically claimed series Adolescence opens with the shock arrest of 13-year-old boy Jamie Miller who is accused of murdering a girl who goes to his school. But is he the killer?

Starring Owen Cooper as Jamie and Stephen Graham as his father, Adolescence reveals the truth about Katie's murder pretty early on in the show. The remaining episodes then dive deeper into the important factors surrounding the "why" behind her death.

Co-creators Stephen Graham and Jack Thorne have now explained why they thought it was key to tell the story this way. And if you're wondering who actually killed Katie, here's your answer...

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WARNING: Spoilers ahead for Netflix's Adolescence!

Did Jamie kill Katie in Adolescence? Picture: Netflix

Did Jamie kill Katie in Adolesence?

Yes, Jamie did kill Katie. It's confirmed at the end of episode 1 that Jamie is the killer when he's confronted by CCTV footage of him stabbing Katie several times the night before.

He'd previously denied all claims when questioned by the police. He was also caught on CCTV cameras with two friends following Katie shortly before the murder occurred.

The first episode ends leaving Jamie's father Eddie (Stephen Graham) crying in disbelief next to him in the interview room as he asks, "What have you done?"

Jamie initially refuses to take accountability for his horrific actions and doesn't appear to realise what he has actually done. In the final episode, Jamie eventually comes around and tells his dad that he's going to plead guilty.

Jamie discussing his relationship with Katie in Adolescence episode 3. Picture: Netflix

Why did Jamie kill Katie?

As the series goes on, it's revealed that Jamie had been engaging with toxic content online that promotes misogynistic and extremely harmful rhetoric against women.

In episode 2, DI Bascombe's son explains the 'manosphere', which consists of several online communities that have been known to radicalise young men. "You must trick [girls] because you'll never get them in a normal way," he says.

He then reveals that Katie had publicly implied that Jamie was an incel in an Instagram comment.

Due to a mix of embarrassment, lack of self-esteem and male rage triggered by the impact of the propaganda he'd been consuming, Jamie violently and fatally attacked Katie.

Adolescence's Stephen Graham reveals the real life events that inspired the show

Explaining why the audience is purposefully made to believe 13-year-old Jamie could never be capable of murder, Stephen Graham told Tudum: "That was down to the casting. We wanted the audience to be on Jamie’s side and think, 'Oh my God, this arrest is terrible. There’s no way he's done this.'"

"We wanted the audience to feel the same feelings that Eddie feels when he looks at it and realizes what Jamie did,” he continued.

Instead of framing the show as a "whodunit", co-creator Jack Thorne explains that it's more of a "why-done-it" and in order to execute that, they had to answer any questions about who killed Katie straight away.

“Questions like, 'What’s going on within our teenage boys?' Phil, Stephen, and I are looking at masculinity — thinking about ourselves as men, the kinds of fathers, partners, and friends we are, and questioning with some intensity who we are as people," Jack explained.

“Telling a drama that’s a why-done-it, rather than a whodunit, hopefully engages people in different questions."