What can I do if my mum's leaving money + estate 2 me but my brother who is pow. of attorney has spent it all?

my brother has talked my mother, who is suffering from dementia into signing over a very valuable piece of acerage to himself, which was the family property, and has now started sub dividing and selling off. As a result my mother was forced to move to her town house, and now has been put in a home. My brother has now sold the town house, and I have not seen a single cent from any of these sales. Also when my mother wanted to start recieving a pension my brother said she would have to transfer her large savings to his and my other brother and sisters accounts. I now realise that she did not have to do this and I have recently found out that my siblings have spent this money