Abusive “caregiver” using addict son. What should we do?

New outside caregiver for woman with Alzheimer’s. 49y/o son has been living in basement for 6 years & providing minimal “care” however if you listen to him he does “everything” with no support or “power.” Obviously using. Manipulative. Angry. Inappropriate. No filter verbally. Police have been involved in the past. Has been to treatment 5-6 times over the years.

Recently told POA - legal, financial & medical - sister and me, “he’s done.” However he will continue to stay in the basement. Witnessed extreme event of verbal elder abuse last week before he said he was done. He wants to take a week off, come back & only have family (his daughter & sister) involved. I have years of Al-anon experience because of my own family as well as award winning caregiving experience.

When no one is around he winds his mother up with lies and manipulation. He leaves and then she attacks verbally and once physically. Police were called. When he’s not around and influencing her she’s a pleasure to be with. Very complicated dynamics.

Daughter/Sister is somewhat in denial because she’s afraid of brother’s anger issues because of history. It’s worse when he’s using. Crack, pot & beer.

I’m encouraging daughter to get a geriatric case manager and an elder care lawyer to make the best decisions possible for her mother and to let them be “the bad person” when it comes to dealing with the son if necessary.

I have mace and I’m recording every interaction I have with him however I’m walking around on egg shells because he’s so mercurial. I’ve suggested video cameras in the kitchen, family room and driveway because that’s where she hangs out the most, he’s verbally & inappropriately spoken to me there & I don’t trust him. People he’s associated with come & go on the driveway. I’ve also requested she take an inventory of all the valuables.