I would report the matter to the police in both California and Houston.
Contact the company issuing the check to stop it and seend a letetr to them threatening legal action if the proceeds are wrongfully disbursed based on a forged signature. That may compel the maker to cancel the check amd would certainly red flag that loan officer to them for future purposes.
Contact the licensing board for realtors in California to inquire how you may file a complaint to have action taken against their license.
Good luck. I hope it works out.