Washington (CNN) -- In his first public comments since a personnel shakeup over the controversial "Fast and Furious" operation by the Bureau of Alcohol, Tobacco, Firearms and Explosives, Attorney General Eric Holder said ongoing investigations will find involvement did not reach "the upper levels" of the Justice Department.
During a televised Justice Department news conference, Holder acknowledged the ATF's gun-running operation designed to track weapons to Mexican drug cartels "was clearly a flawed enforcement effort."
But Holder rejected the idea investigators will find that either he or his top aides had any knowledge of the operation.
"The notion that this reaches into the upper levels of the Justice Department is something that at this point I don't think is supported by the facts and I think once we examine it and once the facts are revealed we'll see that's not the case," Holder told reporters.
The Justice Department Inspector General and the Republican-run House Governmental Affairs Committee are separately investigating the case. Both are expected to continue for several more months.
Holder also defended his decision to transfer rather than fire his ATF director, Ken Melson. "Ken has served this department well over the course of some three decades," Holder said.