Two years ago she was POA for my father and she robbed him blind before he died. All of a sudden I see her showing a sudden interest in my mother and buying her little gifts. It is obvious she is up to something. I was told I have to get Guardianship of my mother but I cannot afford or cannot find a Pro Bono Estate Lawyer in NJ. HELP!!!
If your sister has a criminal record arising from mishandling of funds and fraud against your father, that's a valid enough reason to prevent her from having any access to your mother's financial issues or assets.
Who now is named as attorney-in-fact in your mother's DPOA, if she has one? If you hold it, there's no reason to get guardianship; just contact the police who handled the case for fraud against your father and ask what preventive measures, if not injunctive relief, are available to protect your mother.
Depending on the state she is in, check to see what she has to do as POA. Some states require annual accounts to be filed that detail how the money is spent. The clerk of court should have records of that.
If you still aren't happy, I don't know of any way to get control of the money without filing to be appointed guardian. It's a huge responsibility. You don't have to have an attorney, though it is better if you do. You can go to the section of the courthouse who handles guardianships. There should be a website that gives the forms that are necessary and what is required to have it examined by the court.
Is there some reason you can't just ask your sister what is going on?