Legal Question in Real Estate Law in California

The landlord acted correctly. Tell your roommate that he must pay or you will sue him in Small Claims Court and he will have to pay your costs and will have a judgment against him that will hurt his credit record and perhaps his future ability to rent. Ask him if all that trouble is worth it. Also mention that what he did might be a crime; do not say you will file criminal charges unless he pays you as that is the crime of extortion. Try to have everything in writing so that you have evidence to show the judge, but it does seem to be an iron shut case. You can also complain to the bank that they should not have done what they did and if he still has funds in his account they might put a hold on them until the matter is resolved.

Ask him for your portion of the money. If he does not pay, sue him.

Bank error. It should not have accepted the two-party check without both signatures. Speak with an operating officer at the bank. The bank should, and perhaps can and will, reverse the error and pay you your half. If it won't, take them to small claims. This assumes it was a two-payee check, "ABC and XYZ" rather than "ABC or XYZ" whoich would be payable to either of you and would not require two signatures.