Foreign documents present several challenges. First, how do you locate them? You will probably be limited by what your client provides or what is available on the internet. Unfortunately, most countries don't have easily accessible records (birth certificates, marriage licenses, police reports, etc). Then, if you have documents, are they authentic or fraudulent? What documents are even available for a particular jurisdiction? Try the sources below for more information.
- U.S. Dept of State Civil Documents by Country
Limited info on foreign documents such as marriage, divorce, birth certificates and other documents. Helpful addresses for obtaining criminal or military records. Coverage varies by country.
Surprisingly has images of drivers' licenses, passport, etc. Be specific when searching and include country name.
- Country of Origin Research (Immigration and Refugee Board of Canada)
Some response specifically deal with documentation. Search by using "document" or "passport" and selecting a country.