ATF director Kenneth Melson and the U.S. attorney in Phoenix have both left their jobs over a sting operation, known as Operation Fast and Furious, that inadvertently provided weapons to dangerous drug cartels.

Melson had been the public face of the embattled Bureau of Alcohol, Tobacco, Firearms and Explosives as lawmakers excoriated the agency during a months-long investigation. He is set to become a senior adviser on forensic science at the U.S. Justice Department's Washington headquarters. Dennis Burke, the U.S. attorney in Phoenix, will leave the department.

Operation Fast and Furious sought to track Mexican drug traffickers by allowing illegally purchased firearms to flow across the border. But some of the weapons turned up at the scene of violent battles between drug cartels and near where a U.S. Border Patrol Agent had been murdered.

When our office makes mistakes, I need to take responsibility, Burke said on Aug. 18. This is a case ... it should not have been done the way it was done, and I want to take responsibility for that, and I'm not falling on a sword or trying to cover for anyone else.

Even with Melson and Burke's resignations, the lawmakers leading the investigation appeared to determine to push on. Rep. Darrell Issa, R-Clif., said that the House Committee on Oversight and Government Reform will continue its investigation to ensure that blame isn't off-loaded on just a few individuals for a matter that involved much higher levels of the Justice Department, and Sen. Charles Grassley, R-Iowa, said that he wouldn't be surprised to see more fallout beyond the resignations and new assignments announced today. 

It remains unclear who else will be held responsible for an operation that was plagued by different agencies failing to communicate with each other or the Mexican authorities. In testimony before Congress, ATF agents who alternately described the program as insane and a disaster and said that after they were initially kept in the dark, warnings to higher-ups were rebuffed or ignored. There is also evidence that ATF officals responsible for the program withheld details in updates to the White House.