Need Advice to help my nephew

Hi, this is such a very long story 12 years worth that its hard to know where to begin, i have a 12 year old nephew in a bad situation, his mother has never cared for him properly, including providing for his needs, the rest of the family has mostly done it all. She has not abused him physically, but she has mentally, to the point that he has severe issues going on now and needs to see a psychiatrist, shes told him terrible things, including that he was responsible for killing unborn babies that she claims to have been pregnant with, all of this very UNTRUE! the list is so endless, that i cannot even begin to tell it all at this moment, shes been with very abusive men through out his life, her latest husband being the worst of them, a few weeks ago he grabbed my nephew and punched him in the head until he was unconcious and gave him a black eye, and he beat my sister, police reports were filed at this time, and our state Dept of human resources became involved, but they've been involved for 12 years and have done nothing to protect this child, the state inspected my mothers home which is where they were to stay during this investigation as their place of safety, my sister has serious mental problems including being a pathological liar, and made life unbearable for my mother and her husband, she ended up leaving and walking with her son down a busy highway, later she called a family member to pick her son up. He is now back with my mother who went to DHR, and they did NOTHING basically. My sister is back living with the man that did this to her child, she has no home of her own and no job. Now she is even changing her story and blaming her son for everything..that hes violent and started it, which has us all disgusted beyond belief, no child no matter what they started deserves what happend to him. This child has lots of mental issues, and is now having nightmares and not sleeping, and has learned that his mother returned to the man that hurt him. The DHR office called her husbands parents, which is where they are living and asked if they were there and they said yes, so they know she is back with this man , who has a jail record because of domestic abuse, we believe my sister is not filing charges against him now for her abuse, we're confused on who is suppose to file charges on child abuse..is this not enough grounds to file child abuse charges?? my sister will not protect or stand up for her son, she puts men before him every single time. He has lived with me on and off since his birth, with his mother in very little contact, hes lived with other family members as well. When we asked DHR about removing him from her permanently they just asked us if we had a lawyer, we are all very very confused, this pattern of abuse has went on since his birth, she acutally lost him at 2 months of age for neglect, but i agreed to take them in and they returned him, once out of my care his mother returned to her same pattern of putting her child last in her life. I have done everything i possibly can to protect this child, even consulting DHR in the state capitol. It would take me weeks to write of all the abuse this child has endured. Its absurd when there is so much family willing to care for him and that love him deeply. I have searched and searched the internet for laws pertaining to this case, but i get lost in it all and what it all means. Surely this child has rights, the right to feel loved and protected and to sleep at night without nightmares that someone is trying to kill him. He has rights and i cannot find a single resource or person to turn to that will help me fight for his rights. It seems like the system is fighting against our entire family on this, and only considering his mothers rights. If you ask me she had no right to be a mother in the first place!!!! Is it possible in this case for me to obtain a lawyer and actually gain custody of this child, or at least make sure he is safe? DHR in this state is failing miserably. And its so terribly sad. Why do children have to die before anyone helps?????????????????? someone please give me any advice that you can.. im willing to talk to anyone privately that may be able to help me..this story is just to long to tell here! Thank you!