Seriously, I wouldn't call the sheriff until I talked to an attorney and get the ownership straightened out. You're right, you could lose the whole thing just because you are trying to save some money. There will be legal fees involved with this, I'd get that ball rolling before this hole gets deeper.
I had inherited a building lot in Florida and I met with an attorney referred to me before I got back on the plane. We too found there were taxes due and made arrangements to get those current. It's amazing how much better we slept when the paperwork was 'in good order' and in the scope of the big picture, the lawyer's fees were very reasonable.