I have read that all probable natural fathers are notified if actions concerning custody of child are brought up. The child was given to mothers parents because mother got sentenced to serve time. I was never notified of change of custody, also was informed mother claimed I wasn't the father upon birth.
the child is now 4 and is in full custody of mother who was recently released and who is filing a support case against me. Is there anyone who knows how to approach custody rights if the child is mine?

I have read that all probable natural fathers are notified if actions concerning custody of child are brought up. The child was given to mothers parents because mother got sentenced to serve time. I was never notified of change of custody, also was informed mother claimed I wasn't the father upon birth.
the child is now 4 and is in full custody of mother who was recently released and who is filing a support case against me. Is there anyone who knows how to approach custody rights if the child is mine?

First you will have to ask for a DNA to make sure the child really is yours. If it is, you can file a petition for custody and or visitation rights. If you can provide the child with a better envirionment than the mother can and you want custody, you will need to prove in court that you will be the better custodial parent. It can be very complex, and you really need to have an attorney working on it. Good luck.
Xena

It may be too late, but you need to file an action to establish paternity because obviously paternity is contested and no one is believing you are the legal father and not even you are sure.