Do you have an existing child support agreement? If so, before you go to the DA, go to DSS. Under the Uniform Interstate Family Support Act (UIFSA), which all states have subscribed to, they HAVE to help you - it's a matter of law.
Here's a link to read about what it can do.
http://www.duhaime.org/LegalDictionary/u/uifsa.aspx
The state WILL help you