For PI methods and Techniques, See the WISEwiki page for "Private Investigation":
There are numerous PI databases of value, several of them free of charge. The databases below, in alphabetical order, can be useful, and have information on any charges that may exist, if known:
Ancestry.com: http://www.ancestry.com/ This huge source has 32,547 databases in its collection. Some things are free, but to get to all the databases, you have to pay: US databases: $20/month or $99.00 for six months; World: $35/month; Click here for all subscription options and differences in coverage. Several local public ; libraries have the service, so just go there; Their customer service number is: 800-262-3787, seven days, 9am-11pm, EST.
Familysearch.org: https://familysearch.org/ This is a free database that is similar to Ancestry.com, but without the cost; It has over 4 Billion names, family trees, etc, and has 24/7 free phone support service; You have to create an account, however, which JHR has established. This is the one Ron H. told about.
Archives.com http://www.archives.com/ This is another large database, and is actually part of Ancestry.com, and also has a charge at $9.99 per month, less than the $20 per month of Ancestry, but does not cover as much. They became part of Ancestry.com in 2012. They claim 4.3 billion records of all kinds, including photos, which are in 322 different databases. But many of those 322 listed databases are "not available" according to the database list. For the name Carl Pabst, they had 7,063 records, including 1,582 birth records, 2,269 marriage records, 3,004 death records, and 204 divorce records;
Find a Grave.com http://www.findagrave.com/ This is also part of Ancestry, and has millions of grave sites, and obituaries, including many Hiars of the Carp Lake Township Cemetery.
Rootsweb.com http://www.rootsweb.ancestry.com/ This is also now part of Ancestry.com, but is free. But it doestn't have very many databases.
Intelius: http://www.intelius.com
This is one of the best services, and gives a history of addresses, phone numbers, and email addresses that the person has had.
ICANN Whois Look-up and other domaain look-ups: Identifies who is behind any domain name or website:
KnowX:
Locate Family: A database claiming over 240 million individuals with over two million family names: http://www.locatefamily.com/index.html
Melissa:
NamesDatabase: http://namesdatabase.com/cgi-bin/signup?
NamesDatabase, Wikipedia page http://en.wikipedia.org/wiki/Names_Database
Virtual Gumshoe: a PI resource website from 2002-2017. After 2017, it the Wayback machine no longer captured its website. The last WBM capture was April 7, 2017: https://web.archive.org/web/20170407013313/http://www.virtualgumshoe.com/resources/
Webgator: this was one of the early PI websites that provided links to many useful research sources; It became Virtual Gumshoe in 2002. Its Wayback Machine website for 2001 still has active, good links:
Non-profit Organizations:
Guidestar tax returns for recent 3 years: https://www.guidestar.org/
Propublica has tax returns back to 2000: https://projects.propublica.org/nonprofits/
Property Records
City-County Database to determine the county in which a town or city is located http://explorer.naco.org/index.html?zipSearch#
Nationwide, by State, then County, every county assessors office in the US:
http://publicrecords.onlinesearches.com/Assessor-and-Property-Tax-Records.htm
Nationwide, plus Canada, Search Systems, the second of the two nationwide databases (Systems Search)
Property Records search, Emmet County, Michigan, with clickable map: map:https://emmetcounty.maps.arcgis.com/apps/webappviewer/index.html?id=7426312e77a04530920120153c5a1fef
Property Records Search, Maryland: http://sdat.dat.maryland.gov/RealProperty/Pages/default.aspx
Property Records, New York City , property search by address
Property Records, Nassau County
Public Records: Wikipedia page for public records, with additional links: https://en.wikipedia.org/wiki/Public_records
Searchbug: http://www.searchbug.com/
SuperPages: http://wp.superpages.com/
Switchboard: This is a free service and very useful function: It finds neighbors within an Apartment building. Hence, you could find other people in the Kad., and other buildings;
Voter Registrations for some States, Including Michigan, Ohio, Florida,
Whitepages.com: very comprehensive and up-to-date, but provides only the current address and phone number: http://www.whitepages.com/
Zaba Search: http://www.zabasearch.com/advanced.php