Bankruptcy Law Questions? Ask a Bankruptcy Lawyer.
If you find that this person has filed bankruptcy, you can file a proof of claim in his case. This form allows you to perfect your lien against the bankrupt's estate. If there are no assets, this may not do you any good.
If you can't find the case online, you can call the bankruptcy court clerk's office and they'll assist you with getting a proof of claim form and finding the right case to file it in.