I watched my sister for years being verbally abusive and rejecting to my nephew. I called her out on it and she laughed it off. My mother and I knew the day would arrive when the boy would have problems. He is now in an adolescent psychiatric ward after several verbalizations, ideations and one attempt at suicide with his depression medicine. (he had access to whole pill bottle). His mother has made me the bad guy to deflect her own responsibility and is denying me access to him. He lived with me until he was three and we have always been very close. She and her husband behave as if all the child's problems are his own fault and that have had no complicity what so ever. How do I let the treatment professionals know there is more to this child's story then the parents are revealing?

You call the cops or CPS. Let them know what is going on. Possibly try to file for medical custody

My first thought was also CPS, but given that the child is an in-patient with suicide attempts behind him, most likely CPS is already involved, and hopefully you've already called them to let them know what YOU know. If not, make the call asap.

Apart from that, sometimes CPS takes their time contacting people like doctors and therapists, and the priority is toward talking to the family itself. So if you think there's urgency at all... another thought I had was, if you know the place the child is being treated at, you can just call them directly. They will probably not be able to tell you anything or even confirm anything for you (confidentiality) but that can't stop you from informing them.

I'm happy the kid has a caring aunt. Don't give up.

The child is in a mental health ward , I think that is what you said, so you write them a detailed letter of all of the problems and harm,

It will not get or allow you to see child, but it will inform of them the problems

Thanks for the advice. I didn't know if I could talk with the professionals, but I will now make that effort. Thanks again.