To sue someone for an unpaid bill, you must know where she resides in order to obtain legitimate service of process for the lawsuit. You can trace a person who owes you money by searching various sources such as phone books, newspaper archives and the county's public records.
Search County Records
Perform a search of county assessor and recorder records, often available on their websites, for counties where you know the individual lives or used to live. Real estate records and personal property records must be updated each year, so as long as the individual is paying his taxes, you should be able to locate him. However, that will only work if he owns property; if he rents his house or rents an apartment, he won't show up in county records as a land owner.
Check Criminal Records
Check for traffic tickets, civil lawsuits and criminal charges against the individual you're looking for by searching online court records, such as Missouri's Case.net, to locate a possible address. It's important to have the individual's date of birth, and even a middle initial, to verify that who you're looking for is the same person listed on the cases you find. Some people-search internet sites offer a full background check, which may cost you a small onetime fee. These sites correlate everything from property tax records to outstanding traffic tickets and have the potential to turn up a lot of information about where the person might currently be.
Look in the Phone Book
Canvas phone books or, even better, white pages online. Search by the individual's name, a previous address or even a telephone number to see if she remains in the same location.
Check Social Media Accounts
Who isn't on social media these days? If you have the person's name, you can usually turn up one or more social media accounts on Facebook, Twitter, Instagram or LinkedIn. These accounts will not give you the person's address for privacy reasons, but you can usually turn up a wealth of useful information such as their place of employment and regular hangouts. You can then find him at his favorite haunts. You also get to find out who their friends and family are, and one of those people may be willing to tell you where the person lives these days.
Contact the Person's Employer
If you know where the person works, for example, from his LinkedIn profile, then this may be the easiest way to contact him. An employer will not give you the person's home address, because this is a violation of privacy legislation. However, you generally can get a message to him.
Dig Through the Archives
Rummage through article archives on newspaper websites in areas you know the individual resided at one time or another. Often you will find helpful information, such as marriage announcements, a listing as a surviving relative in an obituary, or even information about a business he opened.
Hire a Skip Trace Agency
Skip trace agencies use the information you give them to basically check the individual's credit and pull up all known previous addresses and personal property, including the addresses associated with that property. The more information you have about the individual the better, especially date of birth and social security number. Alternatively, use a company specifically designed to locate someone who owes you money, such as US Search. These organizations are much like skip tracers, only they don't require as much information. None of these services are free, but they can be a cost-effective way to find someone if all your efforts are turning up empty handed.