Suspect elder abuse, what can I do?

My sister has had responsibility for our aunt who has dementia for about two years now. The aunt lives alone in her own home. An aide comes in for several hours five days a week and does shopping, takes her to appointments and provides some companionship. My sister gives her money to buy our aunt food, toiletries, hairdresser, etc. I never got along with the aunt and did not have much contact with her. Last autumn I realized she had dementia and started trying to spend more time with her. My father has dementia and I am very involved with his care and this aunt lives one hour from me, so I don't have a lot of time to keep closer tabs on her. She gets Meals on Wheels. I went up to visit her this weekend and except for a can of soup, a half-eaten Meals dinner and some fruit, there was no food in the house nor was there any toilet paper or tissues. The sister plans to move her to AL in another state, where the sister will be living part time. I don't think the aunt knows the sister won't be there that much. This also means taking away the aunt's elderly cat, to which the aunt clings. She has taken the aunt's jewelry, which I don't think the aunt knows. The family also wonders about potential stealing from the aunt, who has about $500,000 in assets. She did steal money from our father several years ago. My main concern, though, is the lack of food and toilet paper. My sister and I don't speak because of her refusal to communicate any information about our mother with AD and she boasted she knew our mother was dying before any one of us and didn't inform us. I feel bringing my observations to her attention will do nothing and they are leaving in about one month. Feels to me that State won't have time to be involved and then AL will take care of her. What can I do in meantime? This feels like it could be abuse but my feelings toward sister are so negative, I don't know if I can be objective.