counterinvestigation

plural counterinvestigations

1. An investigation launched in response to another investigation.

   1 more example

   But Mr. Spitzer continued to be pressed on questions related to Mr. Bruno’s travels with state troopers, which the governor’s aides last week asked the state attorney general and Albany district attorney to investigate. Mr. Bruno has accused the governor of having the state police monitor his travel schedule in an effort to uncover politically damaging information, and has called for a counterinvestigation of the Spitzer administration.

   2007 July 11, Nicholas Confessore, “A Mellower Spitzer Emerges, Playing Down Bruno Feud”, in New York Times