(AP Photo/J. Scott Applewhite)

NBC NEWS – A long-awaited report on the U.S. government’s controversial gun-trafficking operation known as “Fast and Furious” released Wednesday found no evidence that Attorney General Eric Holder knew of the botched effort to trace the flow of guns to Mexico’s drug cartels prior to its public unraveling in January 2011.

The report by the Justice Department’s Inspector General Michael Horowitz said there is “no evidence that … Holder was informed about Operation Fast and Furious, or learned about the tactics employed by ATF in the investigation” before Congress began pressing him for information about it in early 2011.

The inspector general did determine that the acting deputy attorney general, Gary Grindler, received a briefing about the ill-fated gun-tracing operation in March 2010, but that the briefing “failed to alert Grindler to problems in the investigation.”

The report also concluded that the operation was “seriously flawed and supervised irresponsibly” by federal officials in Arizona, who allowed it to continue in hopes of scoring a big case against a gun-trafficking organization despite obvious problems.

Click here to read more.