My mom is 89 and has dementia. Let me say there is a substantial amount of money and posessions at stake. She and my now deceased dad made a living will and trust in 2000. My dad passed away 7 years ago. I have 1 brother and he is a prescription drug addict and an alcoholic. He is addicted to oxycodone and he also gives it to my mom which at her age could kill her and is taking advantage of my mom's mental state. In the living will I am to have Power of Attorney and if something happens to me then he will. A month and a half ago he took my mom to her attorney and had her change the Power of Attorney to him. He then changed all the locks on her house so I can not get in.
Suggest you consult with an attorney specializing in Power of Attorney issues.
Wow! what a tough situation. Clearly you will need a lawyer. But before you hire one can you collect some evidence? Any criminal records, people who will testify to drug abuse, photos of prescription drugs at your Mom's house that are not hers, etc.
You should see an attorney ASAP as many things can be changed with a POA even selling property if it is a full POA. You need someone who can put a stop to any of this until a full review is made. Has your mother been diagnosed with dementia? Can it be documented?
Hope you do this soon or it may be too late and most things would need a court order to make any changes at a later time. If that is even possible.
I would like to add: it appears that everything he is doing is legal with a full POA and what you do for your mother or what you have done in the past will not make very much difference, as long as he has a full POA.