My family had a very similar situation: a man who took control of our father’s elderly cousin suffering with dementia in an effort to steal all of his assets. And he did succeed. My father was his next of kin and visited him about 3x a year as he seemed to mentally deteriorate. He then disappeared. Turned out his stepson had sold his house, moved him, taken power of attorney, bought him a new house but as tenants in common which allowed him to assume ownership on our father’s cousin’s death which happened soon after. Meanwhile my father was having to play detective to track his cousin down- found him 3 weeks after he died. Stepson knew about our father and hid his cousin from him. Stepson was 40 when his mother married our father’s cousin (late marriage, wife died soon after so, adult stepson for 5 years with no obligations because my father was next of kin and visited). Definitely a narcissist.

This sort of thing can happen all too easily. The problem is that it’s rare enough for the normal, sane victim to think “this can’t be happening, it’s so brazen, I must’ve got something wrong”. This plays right into the narcissists strategy of carrying on with being brazen, especially if there’s a big dollop of gaslighting and projection (he complained he had to pay for the tombstone so could he please be reimbursed).