Assistant Attorney General Lanny Breuer, whose tenure has been filled with controversy, stands in his office at the Justice Department. (Bill O'Leary/The Washington Post)

The outgoing head of the Justice Department’s criminal division, who presided over some of the largest criminal cases ever brought by the United States but also came under fire in the “Fast and Furious” controversy, defended his legacy Tuesday, saying his prosecutors have worked aggressively to bring criminals to justice.

Lanny A. Breuer, 54, one of the department’s longest-serving assistant attorneys general, oversaw the Deepwater Horizon case against BP, which resulted in guilty pleas to 14 criminal counts, including manslaughter. The company will pay $4 billion, the largest criminal payment in U.S. history, for its role in the 2010 drilling disaster in the Gulf of Mexico.

Breuer also led the department’s prosecution of banks involved in rigging the global interest rate known as Libor, which has led so far to almost $2 billion in settlements and fines. His division brought the two largest Medicare fraud cases in history, in one case charging 111 people and in the other identifying $452 million in alleged fraudulent billings.

“Lanny has led one of the most successful and aggressive criminal divisions in the history of the Department of Justice, accomplishing record penalties in corruption cases at home and abroad and dismantling major organized crime and health-care fraud networks around the country while also protecting the integrity of our banking systems and fighting financial fraud,” Attorney General Eric H. Holder Jr. said.

But Breuer’s tenure also drew sharp criticism. Sen. Charles E. Grassley (R-Iowa) and Rep. Darrell Issa (R-Calif.) investigated his role in the Bureau of Alcohol, Tobacco, Firearms and Explosives gun operation known as Fast and Furious, and called for Breuer’s resignation. After an independent investigation by Justice’s inspector general, the department found no wrongdoing on Breuer’s part.

“The IG looked at this matter and I was completely exonerated,” Breuer said in an interview Tuesday. “The IG found that I did not know about the inappropriate tactics of Fast and Furious. The IG found that I had absolutely no role in the operation.”

In a “Frontline” program on PBS last week, Breuer and the Justice Department were harshly criticized for not bringing criminal prosecutions against any Wall Street executives in connection with the 2008 financial collapse.

“I understand why people are upset,” Breuer said. “But we have 94 U.S. attorneys and they don’t report to me. Not one of them determined that there was a criminal case to be had. These are very complicated cases and they were just simply, on the merits, not cases that could be brought criminally.”

Breuer said Wall Street executives would have been prosecuted if the investigators could have proved criminal intent. “I have the same DNA in all of these cases,” Breuer said. “It’s just not plausible that in one area we would be overly scared and in all the other areas we would be aggressive.”

Breuer, who oversees 600 attorneys across the country, said his division also secured 115 extraditions from Mexico last year, the most in a single year. It also brought charges against 127 members and associates of La Cosa Nostra in the largest takedown of organized crime in U.S. history.

“Lanny leaves a real legacy of accomplishment and success,” said Neil McBride, the U.S. attorney for the Eastern District of Virginia, citing among other cases the prosecution of Lee Bentley Farkas, the former chairman of Taylor, Bean & Whitaker, convicted in a $3 billion bank fraud and sentenced to 30 years in prison.

Breuer worked closely with the Securities and Exchange Commission to publish a Foreign Corrupt Practices Act guide on how prosecutors should enforce the law that prohibits U.S. businessmen from bribing officials overseas. His division’s efforts led to successful resolutions of more than 40 corporate cases, involving eight of the 10 largest penalties in history.

“Lanny stands out as a colleague who gives whatever he can to get the job done,” said Robert S. Khuzami, the outgoing director of the U.S. Securities and Exchange Commission’s enforcement division. “He has served in challenging times, but he never took his eye off the ball, which is to act in the public interest regardless of any pressure or personal consequences.”

Breuer will step down March 1. He said he probably will return to private practice.

“The reason I’m among the longest serving is this has really been my dream job,” Breuer said. “It has been an unbelievable privilege, and I am exceedingly proud of what we accomplished.”