Legal Question in Criminal Law in California

Only the government can prosecute a criminal case. The victim can't. All you can do is make a report to your local police or sheriff's department, and possibly to your local D.A.

You should understand, though, that failure to return something that was borrowed often is not a crime. Even where it is, the crime often cannot be proven beyond a reasonable doubt. Don't be surprised if the authorities do not want to prosecute this case.

You do have the option to bring a civil lawsuit. That may be the only avenue open to you.

Good luck.