Do not know whether the GPA is Registered or not?

Hello Everyone, There is a problem where the property of my Uncle's as been made GPA registered by a guy who we know but not a Blood relative. We came to know through EC of the property that it is showing as he is also the owner REP of GPA holder. He has taken my uncle to the Register office and without the proper intimation he has probably have get that GPA registered and even we do not know about the whereabouts of the GPA copy as he is not co operating to provide the documents to us. What we can do further? Is he has all rights to sale the property on behalf of my Uncle? My uncle is no more now, he got expired recently and the GPA probably has been registered last year. How can we proceed legal actions against him. He is one of a Real estate guy and the property is in Bangalore. We do not have the GPA details to get the Certified copy too and also got an information that only my uncle or the real estate guy who as got the GPA are the only persons who can get the Copy, Is that so? Moreover he is not a Blood relative. Could you please suggest. Many thanks in advance.