A Justice Department Inspector General’s report on the Fast and Furious matter largely exonerates Attorney General Eric Holder, claiming that he knew nothing about the gun-running operation until after the death of a US Border Patrol agent.

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.

This actually contradicts the big report from Fortune which claimed that Arizona ATF officials never intentionally allowed guns to be sold to Mexican drug cartels, and that they couldn’t get sign-off from federal prosecutors to go after the straw purchasers who bought the guns and put them into the cartel members’ hands. So there’s a lot of finger-pointing here, although the IG report does say that prosecutors in the Arizona US attorney’s office “claimed they had no probable cause to arrest any straw purchasers at the time.” That very much fits with the Fortune report.

But the independent conduct of federal prosecutors or local ATF officials does not bear on many of the claims of House Oversight Committee Chairman Darrell Issa, who led the initial investigation into Fast and Furious. A brief recap from Democrats on the Oversight Committee shows where Issa went wrong, according to the DoJ IG:

With respect to the more extreme claims made by Committee Chairman Darrell E. Issa, the Inspector General’s report did not substantiate them. The report did not support allegations that gunwalking was a strategy authorized and approved by the Attorney General, that gunwalking was used as a deliberate strategy to promote stronger gun laws, that the FBI concealed a “third gun” from the murder scene of Agent Brian Terry, or that Department officials intentionally misled Congress during the Committee’s investigation.

In contrast, the report’s findings did parallel many of those set forth in a report issued last January by Rep. Elijah E. Cummings, the Ranking Member of the House Committee on Oversight and Government Reform. That report found that Operation Fast and Furious was the latest in a series of fatally flawed operations run by ATF field agents in Phoenix during both the previous and current administrations.

Again, we have this tension between the IG report and the Fortune report. But you can read either of those and agree that Holder had no notice of the situation, that there was no master plot to cause a spate of Mexican drug cartel violence to build the case for gun control, or that Main Justice lied to Congress. This formed the core of Issa’s contentions on Fast and Furious, and they have been found to not carry any evidentiary basis.

Whatever happened in Arizona, it happened from the ground up many years ago starting under the Bush Administration. It bears little resemblance to Issa’s fevered dreams.