To date, U.S. Border Patrol Agent Brian Terry is the only known related fatality. Two of the weapons were found at the scene of his killing in 2010 in a remote border area of Arizona.

(CNN) -- Mitt Romney's assertion In Tuesday's presidential debate that he'd "like to understand who it was that did this" -- referring to "Operation Fast and Furious" -- was noteworthy following the release of a lengthy investigative report.

The Republican candidate said the botched Southwest border gun-running operation "had been investigated to a degree."

But that appeared to shortchange the 471-page report by the Justice Department inspector general last month, which was widely praised by members of both parties at a congressional hearing.

It also suggested Romney gave an "incomplete" to the extensive series of Republican-led congressional hearings on "Fast and Furious."

The report concluded the controversial operation stemmed from a "series of misguided strategies, tactics, errors in judgment, and management failures" that allowed weapons to reach Mexican drug cartels.

The report said related failures were evident at the headquarters of the Bureau of Alcohol Tobacco Firearms and Explosives, the agency's Phoenix field office and the U.S. Attorney's Office for the District of Arizona.

Romney correctly stated that "thousands of automatic and AK-47 type weapons" went across the Mexican border to drug cartels.

His reference to the weapons being used to kill Americans may have suggested that more than one American was killed by the illegally trafficked guns.

FBI lab analysts have been unable to conclude whether one of those weapons was used to kill Terry.

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