Legally blind person (87) with dementia getting money taken from him by a care giver. I need help.

I was just asked to monitor a 87 year old dementia, legally blind man, she was fired from the agency but still came and takes cash, has her family working and took him to the bank and withdrew $1,000 from his checking account. He says he loves them, but does know that he is getting ripped off, takes his care for day. Does anyone know what I can do to protect him and others, she was fired form visiting angels for doing the same thing to another lady, but will only take cash from this guy. I need help on this one, it is not right.