The New York Times report claims that Jean Richter's inquiry [into Blackwater], though, was abandoned after Blackwater's project manager in Iraq, Daniel Carroll, warned Richter that "he could kill me ... and no one could or would do anything about it as we were in Iraq," according to a memo sent by Richter to senior State Department officials. According to the Times, the American Embassy sided with Blackwater and ordered the investigators out of the country.
http://www.foxnews.com/politics/2014/06/30/state-department-reportedly-was-warned-blackwater-conduct-prior-to-2007-iraq/