Power of Attorney Question

My Aunt passed away last year – my cousin convinced her to change her will to leave him everything and nothing to his brother.  While she was alive, he had power of attorney.  She was receiving checks for some land we sold awhile back – in the midst of  her illness, somebody sent a note to the buyer of the land and instructed them to send the checks to my cousin’s address and not my Aunt.  As he had POA, we knew he could cash/deposit these checks.  However, since she died, these checks which are made out to my Aunt in her name have been and are still being cashed.  Is this against the law and is there anything we can do about it?
After your sunt’s death the power of attorney was no longer effective.  Upon your aunts assets and liabilities became the property of her estate.  The executor or administrator of the estate is responsible for collecting assets and paying any of the estate’s liabilities before distributing the estate to persons named in the will.  If your cousin is the executor of the estate, he would be able to cash the checks on behalf of the estate.
If you believe that your case used undue influence to cause your aunt to change her will, you would need to speak with an attorney experienced in estate litigation to challenge the will.