What can I do if a family member stole my credit card and used it?

If it's your credit card, and you didn't use it for a transaction, and you know your family member did do it because you have some piece of personal knowledge to that effect, it seems to me anonymity won't work, because your testimony is necessary. Otherwise, how can it be established that you didn't use the card for the particular transaction, and how can it be established that your family member did?

Not legal advice, as I don't hold NJ licensure. If you need legal advice, please consult a lawyer who does.