Financial fraud?

My mom had my stepsister as an authorized used for her credit card (Wells Fargo) to help her build her credit score but never took her off when she was older.
Recently my 26 year old stepsister wrongly used my mom’s card and transferred 13,000 to what she claims it’s “scammers”. I talked to my stepsister and she won’t give my mom her money back since she claims she doesn’t have money and doesn’t want to have payments. An attorney I talked to said we cant make a claim and only a police report. Does anyone know what I can do?