My question involves landlord-tenant law in the State of: CA

It seems that my wife was put into collections by our old apartment that we shared with her parents. After looking at the court paper work it looks like someone put her first name only on the lease and she did not sign it. Now a creditor company is telling her she is on the hook for part of the judgment. Now is it a valid lease for her if her full name was not on it and she never signed the lease?