Riverdale fans have uncovered a clue that may answer the show's murder mystery.

Riverdale‘s three week break has been torture for fans.

In the meantime, they’ve come up with a compelling fan theory explaining one of the show’s biggest mysteries – who killed teenager Jason Blossom.

Presenting their case on a Reddit thread, some believe it was Betty, after a scene where she channels a darker, more violent alter ego.

After learning that members of the high school football team had essentially slut-shamed her older sister Polly, Betty and her friend Veronica lured offender Chuck to a house and end up handcuffing him to the hot tub while turning up the temperature to extract information.

During the process, Betty starts referring to Chuck as Jason - Polly's ex boyfriend and the murder victim - and herself as Polly.

When questioned about it after, Betty says she can't remember anything that happened.

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"I wonder if she developed split personality after Polly left and killed Jason as 'Polly'?," suggested one user.

A split personality, also known as Dissociative Identity Disorder, is described as an "involuntary escape from reality characterized by a disconnection between thoughts, identity, consciousness and memory."

Some believe this explains why she's taking such a keen interest in solving the mystery first.

If you believe the theory, it also throws up the possibility that Polly doesn't even exist if she is one of Betty's personalities.

However others were quick to point out the flaw in this, considering we have now seen Polly.

"It doesn't seem plausible that an entire town would go along with humoring her mental illness and dissociative state by pretending Polly is 'Betty', particularly teenagers," someone wrote.

Others say that given that in these shows the villain is usually punished, they don't believe it will be Betty.

"I don't think she'll end up being the murderer. It's still a CW show, not Breaking Bad, so the murderer will have to be punished when discovered, and you can't have an Archie show without Betty. She's one of the core four, along with Veronica and Jughead," one user commented.

While we're not totally convinced, it's certainly interesting...

Where do you stand?