Federal officials say they have broken up one of the largest Colombian drug cartels and made the largest seizure of heroin in a single operation in New York’s history.

At a press conference yesterday, the U.S. attorney for the Southern District of New York, Michael Garcia, and the special agent in charge of the U.S. Drug Enforcement Administration, John Gilbride, said the Colombian government aided in the arrest of 56 drug dealers. Agents confiscated 257 pounds of heroin with a street value of $25 million,121 pounds of cocaine with a street value of $2.25 million, and $3 million in cash, watches, jewelry, and cars.

The U.S. attorney’s office also released the charging documents for 44 of the 56 alleged smugglers, 35 of whom were arrested in America and 21 of whom were arrested on Colombian soil by local authorities. Mr. Garcia said they are awaiting the extradition of nine of the 21 suppliers arrested in Colombia.

Operation Double Identity began in the summer of 2004, when Colombian officials received an anonymous tip with the names of some alleged smugglers. Mr. Garcia called the operation a “new model” of drug-enforcement cooperation. He said it was the first time that an operation targeted suppliers by “reaching back into the source country,” as well as wholesalers and retailers in America. Most narcotics investigations begin by targeting a retailer and then working backward to find the source.

The smugglers hid the heroin inside chair cushions, the soles of sandals, golf bags, and in 44 pellets swallowed by human couriers, a plan Mr. Garcia called “sophisticated.” The drugs followed a route from Cali, Colombia, to two New York-based wholesalers, to retailers in the Bronx who would process the heroin and distribute it throughout the area.

Messrs. Garcia and Gilbride dedicated the bust to nine slain officers of the Colombian National Police Dijin Unit who were working on the operation. “We at the DEA remember our brothers in Colombia who paid the ultimate price,” Mr. Gilbride said, though he said there was no evidence that the agents were killed because of their involvement with the DEA.

With the last of the arrests made yesterday and the last of the drug seizures made in November, Mr. Garcia said the operation is complete and there are no remaining fugitives.

Those who were arrested in America face a maximum sentence of life in prison and a minimum of 10 years. Although a stipulation in the countries’ extradition agreements prohibits America from seeking life sentences for those arrested in Colombia, the U.S. attorney’s office said it would likely seek between 40 and 60 years in prison.