Well if he suffered severe Alzheimer’s he may not have been able to take care of himself. If she put the dog in the crate in the closet and then had a heart attack... he could end up wandering around for days before he ultimately perished, too.
Very surprising they did not have someone full-time or at least every day to come in and visit.
When my FIL had Alzheimers, we learned that in very advanced stages they sometimes can forget to eat.
It is very surprising they did not have a hospice nurse there visiting regularly this is just AWFUL!!