Assistant Attorney General Lanny Breuer has admitted that he made mistakes after he weas  briefed last year about questionable tactics from a Bureau of Alcohol, Tobacco, Firearms and Explosives gunrunning investigation.

Breuer apologized Monday for not raising the issue in 2010 with senior leadership within the Department of Justice as prosecutors moved to try  the case, which spanned back to 2006.

Documents and Justice Department emails sent to the House Oversight and Government Reform Committee  Monday as part of the congressional investigation into the ATF’s gun operation — Fast and Furious — reveal new information into another controversial ATF operation called Wide Receiver.

Operation Wide Receiver predated Fast and Furious, originating in March 2006 during the Bush administration. The ATF and the U.S. Attorney’s office in Arizona were investigating the gun trafficking case but did not press charges until the Justice Department’s Criminal Division Gang Unit went forward with the case in 2009 and moved to bring indictments in 2010.

As Wide Receiver moved closer toward  indictment, Justice Department officials in the criminal division noted serious concerns over ATF’s tactics in the case by letting guns walk into Mexico.

“Been thinking more about ‘Wide Receiver I.’ ATF HQ should/will be embarrassed that they let this many guns walk,” Deputy Assistant Attorney General Jason Weinstein wrote to top officials in the Criminal Division’s gang unit. “I’m stunned based on what we’ve had to do to make sure not even a single operable weapon walked in [undercover] operations I’ve been involved in planning.”

Weinstein wrote in an April 12, 2010, email that he wanted to set up a briefing for Assistant Attorney General Breuer with the gang unit and officials at ATF headquarters.

“Knowing what I now know was a pattern of unacceptable and misguided tactics used by the ATF, I regret that I did not alert others within the leadership of the Department of Justice to the tactics used in Operation Wide Receiver when they first came to my attention,” Breuer said in a statement released Monday.

The documents were released today as part of the congressional investigation into Fast and Furious — the ATF operation that allowed guns to “walk” across the U.S. border into Mexico in an effort to locate major weapons traffickers, rather than catching the low-level buyers. The operation took a tragic toll when two weapons found on the scene where Border Patrol agent Brian Terry was murdered in December 2010 were linked to Fast and Furious.

Breuer and Attorney General Eric Holder have been held to task about what they knew about operation Fast and Furious. Attorney General Holder maintained he did not know the specifics of the ATF strategy when pressed at a Congressional hearing last spring.

“When the allegations related to Operation Fast and Furious became public earlier this year, the leadership at the ATF and the U.S. Attorney’s Office in Arizona repeatedly assured individuals in the Criminal Division and the leadership of the Department of Justice that those allegations were not true.” Breuer said.

“As a result, I did not draw a connection between the unacceptable tactics used by the ATF years earlier in Operation Wide Receiver and the allegations made about Operation Fast and Furious, and therefore did not, at that time, alert others within department leadership of any similarities between the two. That was a mistake, and I regret not having done so,” he said.

As Wide Receiver gets closer to being indicted, Weinstein notes in an e-mail to a Justice Department press secretary, “Can you meet with me [and other officials] … to discuss an impending indictment in a gun trafficking case that has some rather significant (and I hope unique) press challenges?”

Days later on April 30, 2010 Weinstein wrote to Breuer: “As you’ll recall from Jim’s briefing, ATF let a bunch of guns walk in an effort to get upstream conspirators but only got straws [purchasers], and didn’t recover many guns. Some were recovered in MX after being used in crimes.”

The e-mails show that the Justice Department decided to not issue a press release about the case when the indictments were ultimately finalized. The indictments came out on the same day as a Department of Justice Inspector General report on gun trafficking investigations.

In a November 13, 2010 e-mail Jason Weinstein summed up why the Justice Department did not issue any press releases on the issue: “Lot of guns allowed to go south and came out on the same day as IG report on Gunrunner … the case would be weaved into anti-ATF story.”

“There are 652 pages of documents that our investigators will scour over the next several days, beyond the few that the Justice Department pointed out,” Sen. Charles Grassley, R-Iowa, who has been working on the Investigation with the House Oversight and Government Reform Committee, said in a statement.

“At first glance, though, the documents indicate that contrary to previous denials by the Justice Department, the criminal division has a great deal of culpability in sweeping the previous Wide Receiver strategy under the rug and then allowing the subsequent Operation Fast and Furious to continue without asking key questions,” he said.

“Most importantly, officials raised very appropriate questions related to Operation Wide Receiver at the same time that many of these same officials were receiving briefings on Operation Fast and Furious.  It begs the question why they didn’t ask the same important policy questions about an ongoing case being run out of the same field division,” Grassley said.

Breuer is expected to testify by the Senate Judiciary Committee Tuesday on the topic of organized crime.