Lewis & Short

investīgātor, ōris, m. [investigo],

  1. I. he that searches or inquires into, an investigator (class.): acer et diligens rerum, Cic. Univ. 1, 1: antiquitatis, id. Brut. 15, 60: conjurationis, id. Sull. 30, 85.
  2. II. A contriver: malorum, Vulg. Prov. 11, 27.