Who is responsible to help my father with his deteriorating mental health?

I live in a different country to my parents (who do not live in the USA). In October (on a visit for my mother’s 80th birthday) I had to remove her from the family home because my father’s long term psychological abuse of her had escalated because he had developed Delusional Disorder.

He refused to interact with me after that. Before I flew home I went to great lengths to get him an appointment with a psychiatrist and persuade him to attend. Other family members had to fly across the world to put carers in place to help him and to make the necessary financial arrangements to facilitate their independent (from each other) living.

My father was aggressive and abusive towards those that were there to help and refused to co-operate with any suggestions. So is living on his own and relying heavily on ad hoc help from my mother’s friends. He has no friends.

His delusions persist. He had enrolled my mother’s friends with his stories of abandonment and poverty (is telling everyone that my mother has stolen his money and gone off with another man).

My mother’s doctor has told her that she must not go back to the family home and not to interact with him other than by email (because of the abuse).

We have written to all involved to explain the situation including the financial situation showing that he is clearly able to afford support.

His delusions are increasing and he is now saying that he is withdrawing from his psychiatric appointments as his deteriorating behaviour all the fault of the medication that he received from the psychiatrist.

Because none of his children live in the same country, I’m at a loss to work out who should take responsibility for his decent into insanity (he has also been diagnosed with the beginnings of vascular dementia and he abuses alcohol).

I really just don’t know what to do.