State Department Inspector General Howard Krongard, under scrutiny for his brother’s link to the Blackwater security firm, has decided to resign, U.S. officials said on Friday.

Krongard, the State Department’s top investigator, has been accused by current and former subordinates of thwarting probes into waste, fraud and abuse in Iraq, including alleged arms smuggling by Blackwater.

“We thank him for his dedication to public service and wish him well in the future,” State Department spokesman Gonzo Gallegos said.

Krongard last month recused himself from Blackwater oversight after saying in a congressional hearing that his brother A.B. “Buzzy” Krongard, a former executive director of the CIA, had attended a meeting of Blackwater’s advisory board.

Krongard had begun the hearing by denying the “ugly rumors” that his brother was associated with the company, which is under investigation for a September 16 shooting incident in Baghdad in which 17 Iraqis were killed.