Except the incident occurred in New York state and they consulted someone about California state law? I'd guess most states have similar laws so it is a bit of a moot point.
If the criminal/fraudulent activity which occurred in New York was directed from management based in California, wouldn't the crime become a federal one? What if the e-mail trail reveals similar activity in multiple states directed by managers in San Francisco?
Charges can brought in multiple states at the same time, for the same crime which doesn't violate fifth amendment protection of double jeopardy. It's known as the dual sovereignty doctrine.
The FBI only gets involved in the most serious of cases such as organized crime, drugs, gangs, terrorism, cyber crime, etc.
> If the criminal/fraudulent activity which occurred in New York was directed from management based in California, wouldn't the crime become a federal one?
No, though that may make it so that a federal crime (e.g., wire fraud) was committed in addition to any state crime that was committed.