Legal Question in Intellectual Property in California

I assume you are the Web designer here. First, please note that you have mentioned three or more possible court-related approaches to getting paid or otherwise punishing the erstwhile client. These include a criminal prosecution, which would have to originate with the district attorney prosecuting in the name of the People of the State of California; a copyright suit which would presumably need to be brought in a U.S. District Court; and at least indirectly you suggest or propose a more conventional suit for breach of contract and other damages, perhaps for fraud.

You have already taken the first steps toward initiating a criminal case, and the cops have discouraged you.......not surprising at all, considering the financial plight of county governments in California and the cutbacks in the D.A.'s offices, where some counties are no longer even able to prosecute simple misdemeanors. If it looks like it might be "a civil matter," the authorities aren't interested.

As for the copyright-infringement case, this might be a theoretical possibility, but unless you have a reason for wanting the case in Federal court, it's probably a more expensive route and a far less direct theory upon which to get a judgment.

You didn't say how much the client owes you. If you'd be satisfied with $7,500 or less, I would advise taking the matter to Small Claims Court - fast and quite inexpensive. Get and study a book on California Small Claims procedures. If your claim is for over roughly $15,000, you might consider a suit in Superior Court for plain-vanilla breach of contract. I hope you have a signed written agreement and documentation as to your time spent.