Search in the library catalog for the person's name and the word biography, e.g., Abraham Lincoln biography. If you search for the terms as a subject search, the results will all be biographies of Abraham Lincoln.
For memoirs, or writings the person wrote about themself, use the term personal narratives. You might also want to look for diaries or correspondence.
There are some basic biographical reference sources that can give you common information about someone, either so that you don't have to bore the person by asking obvious questions yourself, or so that you don't have to fact-check the internet. That said, Who's Who is not the most reliable of sources, either, so when in doubt, ask a librarian.
Your person might have been in the news, if not national, most local news sources have gone online.