How would i find out if someone had power of attorney over a deceased person?

I had a boyfriend of 9 years we had 1 son together he is 2 1/2 years old..his dad and i had custody papers drawn up and its stated that he was to carry a life insurance policy naming his son the irrevocable beneficiary. he indeed had a VA policy for $50,000 but his mother was the name on it as the beneficiary. These were court ordered and signed by a judge custody papers. His father ped away suddenly and unexpectedly in sept 08 of a mive heart attack. after his death his family no longer wanted to speak to me..afraid i knew about the life insurance, which I did know about. His sister said his mother was power of attorney over him. ifs that's true would she not be responsible for seeing that the name on the policy was changed from her name to his son's name? How can I find out if she truly was power of attorney over his affairs? this may help me in getting the life insurance money for my son where it rightfully belongs. and we did live together we were just not married. please help..thanks