Try a private investigator.
I've went that route Syrenn, any idea of the cost involved, PLUS the Child Support Enforcement Agency will not work with a private investigator. It's just totally fucked up, It's seriously to the point now that my lawyer has suggested suing the Mo Department of Human Services for not doing enough to rectify the situation, but of course that would be outrageously expensive, and I do have a family to support. It's all about balances, on the one hand it's not fair to let her get with it, on the other hand do I bankrupt my family attempting to collect money from her? And as far as my kid is concerned, she isn't his mother anyway, he doesn't remember her anyway, My current wife is mom. Eventually they will catch her, and when they do I hope they use the full weight of the law to punish her if she just refuses to pay, but currently there is only so much I can do.