I need a Lubbock TX attorney who specializes in will litigation?

My Aunt died. She had investments that her step-daughters had put in a TOD 3 weeks before she died suddenly. She had Alzeimer's. We were not notified of her death until after the funeral. She had a will listing the only heirs to be my brother, 2 cousins, & myself. She had no biological children. We are not even certain she married these women's father 6 years ago. We all live in Oklahoma so we need a Texas attorney who specializes in these kind of cases. My brother is the executor & has not been able to get a valid death certificate. We are worried that she was possibly killed & they didn't know there was a will until they found it at her house after the funeral.