Story highlights Sen. Grassley says no one has been held accountable

AK-47 style weapon found after Mexican shootout

U.S. official links it to botched Fast and Furious Operation

Weapons ended up in hands of Mexican cartels, gangsters

A dramatic shootout between authorities and suspected cartel gunmen at a Mexican seaside resort this month has ties to a botched U.S. gun operation.

A U.S. official said Tuesday that investigators have traced at least one firearm recovered at a December 18 gunfight in Puerto Peñasco, across from the Arizona border, to Operation Fast and Furious.

That's the disastrous operation run by agents in the Phoenix office of the Bureau of Alcohol, Tobacco, Firearms and Explosives.

Agents allowed suspected gun smugglers to buy about 2,000 firearms with the goal of trying to find and prosecute high-level traffickers. They couldn't track the firearms and most are believed to have ended up with cartels and gangsters in Mexico.

Many have turned up at crime scenes in Mexico and the United States, including at a shooting that killed a U.S. border agent in 2010.

The shootout in Puerto Peñasco, also called Rocky Point by Arizona tourists, two weeks ago left at least five suspected cartel gunmen dead, including possibly a high level Sinaloa cartel chief, according to Mexican authorities.

Witnesses reported hours of shooting and grenade explosions, with Mexican authorities using helicopters to attack fleeing suspected cartel gunmen on the ground.

Guns recovered at such scenes are routinely checked with the ATF's tracing lab to try to determine their origin. At least one AK-47 style firearm was found, and U.S. investigators identified it as one that was allowed to be sold to suspected traffickers as part of Fast and Furious, according to the U.S. official.

The ATF, in a statement, said: "ATF has accepted responsibility for the mistakes made in the Fast and Furious investigation and at the attorney general's direction we have taken appropriate and decisive action to ensure that these errors will not be repeated. And we acknowledge that, regrettably, firearms related to the Fast and Furious investigation will likely continue to be recovered at future crime scenes."

Guns from Fast and Furious have turned up at other high-profile killings in Mexico, including those of the brother of a Mexican state prosecutor and of a beauty queen.

The Fast and Furious operation gave rise to more than a year of political controversy for the Justice Department.

Rep. Darrell Issa, R-California, and Sen. Charles Grassley, R-Iowa, led a congressional probe to determine how it came to be approved.

Eventually, House Republicans sanctioned Attorney General Eric Holder for contempt of Congress in a legal dispute over the White House's refusal to turn over documents.

Holder has said tactics used in Fast and Furious never should have been allowed. A Justice Department inspector general report cleared Holder of wrongdoing and placed most blame on officials at the ATF and the Phoenix U.S. attorney's office for failing to properly oversee the agents running the operation.

Grassley, in a statement Tuesday, said: "In Operation Fast and Furious, the Mexican drug cartels found an easy way to supplement their own illegal ways. Worse yet, the Obama administration has yet to publicly hold anyone accountable for this disastrous policy. Unfortunately, guns from Fast and Furious will be found in operations like this for years to come."