Free public records of deceased persons can be found through a variety of independent websites, the National Archives, the Census Bureau records from 1850 to 1880 and records kept by local authorities. A Freedom of Information Act request can also be filed for federal records.
The Social Security Administration created a database containing records of deceased individuals called the Social Security Death Index, which possesses records dating back to 1936. This database is not directly available to the public, but it is distributed to companies that then offer the information to users, often for free. The National Archives' Vital Archives has a sizable amount of death records on individuals who either died during military service, who are reported as POW-MIA or who were former slaves.