Family property dispute and I Suspect to be cheated by brother

We had family property in name of my Mother. We are three Elder brother and Myself is youngest. Papers of the property is in elder brothers custody. Few months back I shifted to new place. Now I suspect that by my elder brother transferred the property in his name or prepared some power of attorney or some deed by misguiding my mother. My mother inform that she has signed some paper without checking as asked by elder brother. Now what to do? And how can take precaution without telling my elder brother?