Michael Horowitz testified on the findings in the Department of Justice Inspector General’s report on the FBI’s “Fast and Furious” operation. He described a series of missteps and failures that led to the use of gun walking during two arms smuggling investigations. He said Attorney General Eric Holder first learned about the tactic from Congress, noting that other Justice Department officials either failed to recognize warning signs or did not share information when they should have. 
“Fast and Furious” was a government gun smuggling sting operation run by the Bureau of Alcohol, Tobacco, Firearms and Explosives between 2009 and 2010 with the goal of bringing arms smuggling charges against Mexican drug cartel members. "Gun walking" was an investigative technique in which weapons were allowed to be smuggled across the Mexican border, with the intent of making arrests later.