By Aruna Viswanatha
WASHINGTON (Reuters) - Units of the U.S. Department of Justice "seriously" botched an investigation into a suspected trafficker of grenade parts and failed to adequately consider the public safety risk posed by letting the suspect walk free, a watchdog for the agency said on Thursday.
The probe had been tied to Operation Fast and Furious, a failed effort by the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives and the U.S. Attorney's office in Arizona to stop gun smuggling across the U.S. border with Mexico.
ATF agents learned in 2009 that Jean Baptiste Kingery, a U.S. citizen, was buying large amounts of grenade components online, and suspected he was transporting them to Mexico, according to the report, from the Justice Department's inspector general.
Border patrol agents stopped him in 2010, but U.S. law enforcement authorities let Kingery go after questioning him and soon lost contact.
Kingery, who was arrested in Mexico in 2011 and accused of trafficking grenade and gun parts to the Sinaloa cartel, is facing prosecution in Mexico.
"We found that the investigation of Kingery was seriously flawed...and that Kingery should have been arrested and charged...long before he finally was," the inspector general, Michael Horowitz, said in the report.
In a statement, the Justice Department said the individuals responsible for the operations have been reassigned or have left, and that the agency took "aggressive action" to make sure it didn't repeat the mistakes.
(Reporting by Aruna Viswanatha; Editing by Alan Crosby)