WASHINGTON - A key figure in the federal gun-tracking operation that is under fire for helping to put sophisticated weapons into the hands of Mexican drug cartels also played a central role in a similar sting involving Twin Cities gangs a decade ago.

George Gillett Jr., a supervisor in the federal operation in Arizona known as Fast and Furious, is now a cooperating witness in the congressional investigation that could lead to an unprecedented contempt citation against U.S. Attorney General Eric Holder.

As a leader in Fast and Furious, congressional sources say, Gillett has been instrumental in determining who in Washington provided oversight for the operation and whether top federal officials had sanctioned such gun stings before.

The Justice Department and the Bureau of Alcohol, Tobacco Firearms and Explosives (ATF) initially denied that they had approved the controversial "gun-walking" tactics allegedly used by Gillett and other Arizona agents investigating gun-trafficking networks along the Mexican border between 2009 and 2010.

Interim ATF Director B. Todd Jones, the U.S. attorney for Minnesota, was brought in by President Obama to guide the agency through the political turmoil. He has acknowledged ATF "mistakes." But an ongoing standoff over Justice Department documents has sparked a classic Washington clash between Obama's claim of executive privilege and congressional Republicans' accusations of a White House cover-up.

Calling the Arizona operation "reckless," a House report blamed ATF for failing to make arrests in suspicious gun sales and stop the flow of weapons before they reached the border. Instead, congressional investigators allege, the ATF, with the backing of Holder's Justice Department, allowed nearly 2,000 weapons to disappear from view in a "hapless plan" to connect suspicious gun store sales in Arizona to a Mexican drug cartel.

As for dismantling a Mexican drug cartel, the House report said, "ATF never even got close."

'Must never recur'

Law enforcement officials say the Minnesota and Arizona operations, while unrelated, raise similar concerns about allowing guns to fall into criminal hands -- sometimes with deadly results.

In 2010, U.S. Border Patrol agent Brian Terry was fatally shot by Mexican bandits who used two AK-47-style rifles traced back to the Arizona program. The incident spawned the congressional probe and set off a storm of recriminations at the Phoenix ATF office, where Gillett was the assistant special agent in charge.

Many of the same questions were raised about ATF operations in the Twin Cities in 1996, when Gillett was a street agent tracking gun store sales to "straw buyers" working for suspected gang members. Some of those guns turned up in drug busts and crime scenes, including one that was found at the scene of a deadly shootout in north Minneapolis.

Gillett, now reassigned to Washington, declined to comment publicly on his role in the congressional investigation. He was one of two agents from the Minnesota ATF office who played supervisory roles in Fast and Furious. The other was David Voth, a younger group supervisor who was not around during the controversial Minnesota case that saw more than 150 guns flow into the Twin Cities' criminal underworld.

Jones is the Obama administration's point man on restoring trust in the ATF, leading an agency split over Terry's death. Agents-turned-whistleblowers have told Congress that their warnings were dismissed by Gillett, Voth and other supervisors. According to congressional investigators, Gillett faced his own fears of reprisal from ATF higher-ups and asked that his cooperation with Congress be officially disclosed.

In a statement to the Star Tribune, Jones said Holder "has acknowledged that certain tactics utilized in Operation Fast and Furious were unacceptable and must never recur."

Echoes of Minnesota

The allegations in Arizona echo criticisms of the ATF's Minnesota operation. Mark Koscielski, a federally licensed firearms dealer and south Minneapolis gun store owner, was fighting the city over zoning at the time. He also was cooperating with Gillett and other ATF agents in tracking gun sales to suspected gang associates -- often young women with no felony records who could easily pass criminal background checks.

The issue in both the Phoenix and Minneapolis operations was one of tactics: Whether to seize firearms from criminals as soon as possible or let them "walk" to identify higher-ups in trafficking networks.