Q: What should I do if a journal doesn't act regarding a paper with serious misconduct?

Detailed Question -

I am aware of the story of a serious misconduct (data fabrication). I contacted the journal's editor months ago, explained the problem and sent him the data and the proofs of the misconduct. It is clear that what the authors did was unethical but the editor doesn't seem to be planning to take any action. One of the authors is a well known expert in the field with many publications in reputable journals.
What should I do in order to retract this fake paper and protect scientists from getting wrong information.
Thank you.

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