BOSTON — An investigation on three continents that started in Boston nearly five years ago has led to drug trafficking and money laundering charges against 20 people and has crippled a major Colombian drug cartel, federal authorities announced Thursday.

U.S. Attorney Carmen Ortiz announced the charges alongside investigators from Italy and Colombia. She predicted the charges — and the seizure of many millions of dollars in drug proceeds — will seriously disrupt the activities of La Oficina de Envigado, a successor to Colombia’s defunct Medellin cartel that has tentacles in Europe, the Caribbean and Latin America.

She said the cartel is considered “one of the largest and most dangerous drug cartels in Colombia.”

“If we can hit them where it hurts, we can make a serious dent,” she told reporters at Thursday’s press conference.

Three of those charged are Massachusetts residents, Ortiz said. One remains at large. Others suspects were arrested in Colombia or Venezuela. Extradition proceedings are under way to move them to the U.S. for prosecution.

In addition, 48 U.S. bank accounts were seized. Ortiz said authorities don’t know how much money was in the accounts but hundreds of millions of dollars had been seized over the course of the investigation, begun with the work of a local undercover officer.

Those arrested were involved in a complex web of money laundering and cocaine and heroin trafficking in several countries, Ortiz said. Investigators pursued leads in the U.S., Europe and several Caribbean and Latin American countries.

The investigation started with an unidentified Massachusetts state police officer working undercover in East Boston. Authorities worked their way up the criminal chain, ultimately linking the cartel to drug sales in Chicago, Los Angeles, New York, Houston and other cities.

“What we’ve been able to do is stop the money, which in effect kills the organization,” said Matthew Addington, assistant special agent in the Drug Enforcement Administration’s Boston office.

The charges announced Thursday are the latest in a long fight against La Oficina de Envigado that has led to dozens of arrests and the seizure of hundreds of millions of dollars and thousands of kilograms of cocaine and heroin.

La Oficina de Envigado was formed by remnants of what was once Colombia’s most fearsome cartel, according to Brigadier General Cesar Augusto Pinzon Arana, commander of the Colombian national police’s antinarcotics unit. He joined Ortiz Thursday and predicted the investigation could forever cripple the drug organization.

“The organization is what remains of what used to be the Medellin cartel, which caused many deaths in Colombia,” he said through an interpreter. “But thanks to this transnational cooperation against drug trafficking we have succeeded in (bringing about) the final stage of this organization.”