muckraker

muck +‎ raker. Believed to have been coined following a 1906 speech by United States President Theodore Roosevelt, in which he likened the investigative journalist to ‘the Man with the Muck-rake’, a character in John Bunyan's Pilgrim's Progress.

muckraker (plural muckrakers)

1. (US) One who investigates and exposes issues of corruption that often violate widely held values; e.g. one who exposes political corruption or the poor conditions in prisons.
   • 2018 August 31, Tyler Pager; Jaclyn Peiser, “The Village Voice, a New York Icon, Closes”, in The New York Times‎:

     The paper gave a start to the theater critic Hilton Als and the novelist Colson Whitehead, both recipients of the Pulitzer Prize. Its resident muckraker, Wayne Barrett, took aim at New York developers and politicians for nearly 40 years, and his obsessive work on Donald J. Trump has become a resource for reporters covering the president today.

2. (Britain) A sensationalist, scandalmongering journalist, one who is not driven by any social principles.
3. (US, historical) One of a group of American investigative reporters, novelists and critics of the Progressive Era (the 1890s to the 1920s)

• muckraking