Source : Webster's Revised Unabridged Dictionary (1913)

Muckrake \Muck"rake`\, v. i. [imp. & p. p. {-raked}; p. pr. &
   vb. n. {-raking}.]
   To seek for, expose, or charge, esp. habitually, corruption,
   real or alleged, on the part of public men and corporations.
   On April 14, 1906, President Roosevelt delivered a speech on
   ``The Man with the Muck Rake,'' in which he deprecated
   sweeping and unjust charges of corruption against public men
   and corporations. The phrase was taken up by the press, and
   the verb to

Source : WordNet®

muckrake
     v : explore and expose misconduct and scandals concerning public
         figures; "This reporter was well-known for his
         muckraking"