Journalists, cops and PIs do, essentially, the same thing, just for different audiences.  Tamara Thompson, a licensed private investigator in California, describes her areas of interest as:

“INTERNET: Researching internet news, company background, products and personal profiles.


ADOPTION: Locate any birth parent or child who was born in California, then given up for adoption.


BACKGROUND: I develop deep background on companies and individuals
related to personal habits, interests, activity, assets, business,
political and social associations, employment, litigation and, business
reputation and business ownership.”

That said, her blog, PI News Link, is a good, new resource related to public records.