Debt follows you everywhere. But the answer to your question about statute of limitations may have a complicated answer. To my knowledge, the statute of limitations depends on the state in which you "currently" live. Check out the link below and see what statute of limitations applies in your state:http://www.bankrate.com/finance/credit-cards/state-statutes-of-limitations-for-old-debts-1.aspx
Since you said one letter suggested a threat of court action, it might be a good idea (unless you live in Wisconsin) to have a brief introductory visit with a bankruptcy attorney. If you live in Wisconsin, consider seeing an attorney who does "Chapter 128" filings. In either case, be sure to show up with recent copies of credit reports from Equifax, Experian & TransUnion. If you don't have them, you can get them free (yes, really free) from:http://annualcreditreport.com
P.S. No, they cannot put you in jail for being in debt. All they can do is sue and seek judgments and leins.