Sorry no one picked up your question earlier. Everyone must be out on a date!
Anyway, the answer to your questsion is that only the county district attorney can prosecute an extortion charge under California law. So, if that's your goal, then the police or the DA is the only place to go with your complaint.
However, just so you understand, the DA may not agree that your former worker was committing extortion -- and if not, then there would be no prosecution.
Hope this helps.
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