Any advice on POA abuse, so I know what to take to DA?

My mother who lived with my sister was diagnosed with terminal cancer back in November. When we looked into her finances to prepare for her final expenses we discovered that all of her money was gone. Sister had POA and was grossly misusing funds for her own benefit. My mother passed away a few weeks ago. My father worked very hard to make sure that she would have money for proper care when she needed it. Instead all we could do was rely on Hospice Care which is a joke. My siblings and I were left to deal with trying to care for her without any medical experience. Only doing what Hospice told us. It was a horrific ordeal for my mother as well. We should have had plenty of money to hire a full time RN to help her stay comfortable and address her final needs. We are all very angry about what the sister did and when we ask her for explaination she refuses and is very ugly. I have all back statements, cancelled checks and copy of POA. I want to take this information to the District Attorney to see if I can have her prosecuted for Abuse of POA. Any advice on how best to approach DA would be greatly appreciated. Anyone with previous dealing with similar situation your thoughts and experience would also be greatly appreciated. Thanks