Great grandmother's will.

So recently my great grandmother passed away. I never really knew her but apparently she was adored by my mom. We were let known that some years ago she made certificates of deposits for each of our 6 family members to be given to us at the time of her death.

Here's my problem, we know next to nothing else because the one handling the information happens to be my estranged grandfather, and he is refusing to give us anything in the way of who her lawyer was, what bank the cds were at, or anything. We've tried to reason with him, but he is an utter dick. It's gotten to the point my mom was in tears and just wants to forget about it all, but I don't want to give him that satisfaction.

What should I do?

In central Ohio, not sure if it matters in this case.