Documents obtained by the Los Angeles Times show Manuel Fabian Celis-Acosta, suspected of having ties to a top Mexican drug cartel member, was stopped in Arizona with 74 rounds of ammunition and nine cellphones, the newspaper said Monday.
He was questioned in May 2010 and released after pledging to cooperate with investigators but then disappeared into Mexico. He was not arrested until February 2011 -- after the federal operation ended.
Law enforcement officials say letting Celis-Acosta go free in 2010 was a crucial blunder, although one official said agents may have been hoping he would provide access to the cartels, the newspaper said.
The Bureau of Alcohol, Tobacco, Firearms and Explosives said it could not comment on the documents because the criminal case is still in the courts.
The Justice Department's inspector general, U.S. Rep. Darrell Issa, R-Calif., and Sen. Charles Grassley, R-Iowa., are investigating the tactics used in Fast and Furious, which began in 2009.
Internal ATF documents said Celis-Acosta, 24, was one of the main targets and was allegedly paid from drug proceeds to acquire firearms for cartels, the newspaper said.
He has pleaded not guilty to gun-smuggling charges.