New York (CNN) -- A Russian cargo pilot and his Nigerian broker were found guilty on Thursday of conspiring to traffic more than $100 million worth of cocaine into the United States and Europe from ports in West Africa.
Federal prosecutors say Konstantin Yaroshenko, 42, and Chigbo Peter Umeh, 43, were arrested in Liberia in May after trying to bribe high-level Liberian government officials -- including the son of President Ellen Johnson Sirleaf -- in an effort to safeguard the route they used to bring Colombian cocaine to market.
Sirleaf's son, the country's national security agency director, and his deputy had been working with the U.S. Drug Enforcement Agency as undercover agents, unbeknownst to the two alleged traffickers, prosecutors said.
The men were convicted on conspiracy charges related to at least three large trans-Atlantic shipments of cocaine that were to transit through Liberia, according to a statement from the U.S. attorney's office in New York.
"This is absolutely a trend we're seeing coming through West Africa and on to Europe," said Dawn Dearden, a spokeswoman for the DEA.
She cited market incentives as a primary motivator for the shipments' meandering routes, often considered vulnerable to international scrutiny.
"What you can get for a kilo in Europe is a lot more than what you can sell it for in South America," said Dearden.
Prosecutors say at least one 4,000-kilogram shipment -- itself worth more than $100 million -- was supplied by the Revolutionary Armed Forces of Colombia, commonly known as FARC, a leftist rebel group funded by way of narcotics sales and kidnappings.
The cocaine, often grown in the FARC-controlled stretches of rebel-held Colombia, was to be first delivered to Venezuela before heading to Liberia, a way-station for further distribution.
Prosecutors say the pair agreed to make payments in the form of cash and cocaine to facilitate the transfer of the narcotics for at least one shipment to New York by way of a commercial airline flight from Ghana.
Umeh, who prosecutors said served as a broker between suppliers in South America and distributors in West Africa, faces a minimum of 20 years in federal prison.
Yaroshenko, a pilot who -- according to the U.S. Justice Department -- transported thousand-kilogram quantities of cocaine through South America, Africa, and Europe, will face a minimum term of 10 years in federal prison.
The 42-year-old-cargo pilot was held in the same pre-trial detention facility in New York as suspected Russian arms dealer Viktor Bout.
The so-called 'Merchant of Death' is now in U.S. custody awaiting trial on charges that he agreed to sell millions of dollars of weapons to the FARC.
Meanwhile, Russian officials have argued that Yaroshenko's apprehension and incarceration "directly violate norms of international law."
"We are talking about kidnapping of a Russian citizen on the territory of a third country," a Russian Foreign Ministry statement said in July. "The actions of the U.S. special services at forcibly and secretly transferring of our citizen from Monrovia (Liberia) to New York can be qualified as outright lawlessness."
Yaroshenko's arrest marks the first prisoner transfer from Liberia to the United States in connection with a narcotics-related charge in more than three decades, according to the U.S. Justice Department.
The two men are scheduled to be sentenced in U.S. federal court in New York on July 28.