It started as an attempt by federal agents to build large criminal cases against high ranking Mexican drug cartel leaders.
It quickly devolved into hearings before Congress, demands for resignations, officials quietly transferred out of the border region and, possibly, the death of a U.S. Border Patrol agent.
The ATF is accused of running an operation it called Fast and Furious that allowed cartel gun buyers to purchase weapons and take them unhindered into Mexico. Some 2,500 guns were reportedly smuggled into Mexico as part of this operation.
The backlash against ATF started in January when some of those American weapons turned up at the scene of the shooting death of Border Patrol agent Brian Terry. He was shot and killed by bandits in a canyon just north of the Mexico border, officials said.
According to officials, the gun sting operation can't be laid solely at the feet of the ATF. Other federal agencies were involved.
"This is all part of a collective strategy to go after cartels through a number of different avenues," said Michael Bouchard, a retired ATF assistant director. "There was a number of different plans of attack."
He was surprised when Fast and Furious surfaced as a scandal singling out ATF. The sting idea is a common one: Drug agents will let a narcotics purchase go through to build a case. IRS agents will watch people transfer money before making an arrest.
"Guns are a little bit different because the outcome could be significantly different," Bouchard said. "But, overall, when you have a multi-agency case going after high-level people, one agency is not going to decide how this case will be run."
He says an operation like Fast and Furious would be just one of a number of different investigations, all coordinated by the U.S. Attorney's Office in Phoenix.
Dennis Burke, the U.S. Attorney for Arizona declined to comment for this story.
He emailed a statement that essentially justified the results of the operation.
"So far, 20 defendants have been federally indicted as a result of this prosecution effort on an assortment of federal gun crimes, drug offenses and money laundering," Burke wrote in the statement.
In fact, the Fast and Furious operation was probably the result of pressure on the agency to come up with results.
Colby Goodman is a weapons trafficking expert in Washington, D.C.
"I think one of the reasons why the ATF agents in Phoenix perhaps took a more risky approach is that there was a new policy initiative last year to go after what's sometimes called the brokers," Goodman said. "(These are) the individuals behind the scenes, directing straw purchasers, individuals, to buy guns illegally for them and then traffic them down to Mexico."pe="oembed" width="300" align="left" >http://www.youtube.com/watch?v=MLcNw1HV_tg
Still, Republican members of Congress are calling for ATF's acting director to resign. And investigations into the operation continue.
In testimony before the House Committee on Oversight and Reform last week, officials from the U.S. Department of Justice refused to give more information about the gun-running sting, saying their own agency's Inspector General is looking into it.
In the meantime, the murdered Border Patrol agent's family has hired a high profile lawyer to investigate Fast and Furious and the agency's role in his death. The lawyer, Paul Charlton, is the former U.S. Attorney for Arizona.
"We're doing our own investigation and then we'll make a determination as to what if any action we should take," Charlton said.
Back in Washington D.C., Congressional hearings will continue through the summer.