This is a tragic situation. By law, your dog would likely be deemed "dangerous" by the courts with many parameters for keeping it away from people or other animals it could harm. Family member is in local animal control and you won't find a rescue or resource to work with the dog...killing another animal is a no go. Ask your vet what is the best case scenario for this animal if you cannot keep it controlled/confined to ensure the safety of humans or animals around it.