I have always tried to do what was right. The mother moved while I was overseas in the military still making payments. No forwarding address was left. When I contacted the court they were unable to produce a forwarding address. This can be confirmed by the Tennessee CPS division. I tried to make payments and was told I could not and they would not hold the funds I paid. They sent the overpayments back to me and stated the case was closed and I could do nothing else. They did not have an address for the mother and neither did I. The mother was now married and the husband told me they did not want child support from me and that they did not want me to have anything to do with my son. I had not heard from my son in over 11 years when the mother called me and said he had questions and wanted to get to know me. I found out it was because the mother and father were then having troubles and she saw my picture on the internet due to me doing some modeling. I was contacted by the State of TX Attorney General's office stating I owed more than 21,000 USD in back child support. I called TN and they said this should not be since the case was closed and there was no way for me to pay to the account. I believe the case has been closed for more than the 6 years since the last payment. The funds were returned to me for the overpayments which came to a few thousand dollars. NY is now withholding funds from my paycheck for arrears, current support due, and most recently the put a lean on my bank account. I really need to stop this madness. How do I get that 12 years back? How do I get this arrears removed as the case was closed and I could not pay? How do I get justice in these precedings? Please assist.

You need a family law attorney to represent you in the matter. I don't think you will be effective in fighting it on your own. It will be helpful if you can prove your attempts to pay in the past. It will also be helpful if you can prove that your child's mother refused your efforts to pay support. And, you can certainly file charges against her for denying you access to your child and disasppearing with the child.
Perhaps if you do this, she would be willing to drop her petition if you drop yours, and leave it at that.

You should contribute to the child's care moving forward, but you should also have access to the child for parenting time. Being held accountable for support she refused for years though, I think you might have a chance to get out of that.

First off you need to find out how the Texas AG opened a case against you. You will need more details as to what will happen next. You may have to revisit the child support issue in the Texas court system so everything gets straightened out.