What can I do to revoke and/or prosecute my sister who is an abusive POA of our 89-year-old frail mother with Parkinson's?

Without getting into too much of a background of my sister, suffice it to say, she is taking advange of our (5 of us) mother and isolating us from her. My red flags;

1. Acts like she is our mother's legal guardian (my mom is her own person) and routinely tells her and makes her do my sisters bidding. My mom lives in her own house but is cared for primarily by my two sisters who take turns living with her. My POA sister lives in Tyler Texas, and will take my mom against her will down to Tyler as a matter of convenience to my sister by being with her own family despite my mom wanting to stay in her own home.

2. My POA sister absolutely hates our brother who was once the live in cargiver for my mother. She extorted my mother's signature on her own pre written letter stating my brother could never set foot in the house again. My POA sister threatened to basically abandon my mother and insinuate she would be put in a nursing home unless she signed it. My mother has since confided that she feels horrible about not having her son allowed in the house and states, "I wish I had never signed that".

3. The POA sister once stated, when my dad died, that mom had more money than she would ever be able to spend in her lifetime. Now, my sister states that "there may not be anything left by the time mom goes". Mind you, it is not about the money, but the corruption regarding my mothers mother's estate.

It is to be noted that my POA sister refuses to let anyone know any information regarding the finanical health of my mother's estate and has, I learned through a background check on her, that she has been employeed with an elder care company(my mom is the only person elderly she deals with) . I believe she is getting billed medicare money off our mother utilizing her married name to hide impropriety. .

My sister has my mom so scared of being abandoned and has been brainwashed into thinking that she is the only one capable of having authority, my mom gives her free reign under threat of abandonment. I have been licensed in the health field for over 20 years with 17 in the geriatric population. My sister not only will not listen to advice on medications or symptoms detrimental to mom, but only put herself on the hospital list when my mom was in the ICU with flu, congestive heart failure etc. My sister doesn't turn on my moms answering machine at her home, and doesnt let her have her phone and screens her calls.

I believe my sister is guilty of emotional/mental abuse for forcing my mom to ban her son from visiting. I believe she is funneling money from my all of my moms investments without her knowledge and I believe she is not acting in the best interest of my moms health. what do I do? All my other siblings are silent and under her thumb. I don't care about anything other than stripping my sister of her abusive power and protecting my mother.