Eight members of an alleged Colombian drug trafficking ring in Colombia have been arrested and will be prosecuted in Boston after federal agents followed a money trail to the South American country, federal authorities said Thursday.

Three tons of cocaine that authorities said was bound for the United States was seized in Colombia during the five-year investigation, said Carmen Ortiz, U.S. Attorney for Massachusetts.

Five of the suspects have been extradited to Boston, where officials say they will be prosecuted on a charge of conspiracy to import cocaine into the United States. The three others are expected to be extradited to Boston later.

Ortiz said the investigation, dubbed "Operation Beanpot," began in Boston in 2005 when federal drug agents, posing as money launderers, made contact with members of the drug ring and were hired to handle some of its money transfers.

During the investigation, the U.S. Drug Enforcement Administration coordinated undercover operations in the United States and around the world and transferred millions of dollars through undercover accounts back to accounts controlled by the traffickers.

Using investigative leads obtained by the DEA in the Bahamas in 2007, Colombia's Administrative Department of Security — the equivalent of the FBI — obtained authorization to intercept conversations on several Colombian cell phones, according to an affidavit filed in court. As a result of those telephone interceptions, Colombian authorities seized more than 2,900 kilograms of cocaine allegedly belonging to the drug ring.

Authorities say among those arrested was the leader of the alleged ring, Leyvan Alvarez-Bastidas, 39, and several of his lieutenants.

Ortiz said that typically, authorities find drugs, then follow the drug trail to the money.

"In this case, the exact opposite was true," Ortiz said during a news conference to announce the arrests.

The cocaine seized during the investigation was worth at least $100 million wholesale and much more when sold on the street, Ortiz said.

In the affidavit, authorities said Alvarez-Bastidas is the leader of a large drug trafficking organization that imports cocaine into the United States using Filipino merchant marines working on commercial container ships.

According to the affidavit, Hector Javier Castro-Meza, one of Alvarez-Bastidas' lieutenants, instructed the marines to smuggle cocaine to New Orleans.

The charges carry a mandatory minimum term of 10 years in prison and a maximum term of life.