The plea was entered Thursday by Mario Villanueva, former governor of Quintana Roo state, home to the posh resort town of Cancun.

Villanueva was extradited to the United States in 2010 and could face a sentence of up to 20 years.

Before a judge in U.S. federal court, he said he had participated in a conspiracy from 1993 to 2001 to conceal the origin of illicit drug money (link in Spanish).

The original indictment said Villanueva "was paid between $400,000 and $500,000 in cash for each load of cocaine that [the Juarez cartel] brought into and shipped out of Quintana Roo," which added up to millions of dollars in the 1990s. "In return, [he] provided state and federal police and other resources to offload, transport, store and protect the cocaine shipments."

Villanueva's case involved the laundering of profits through money transfers administered by Consuelo Marquez, a Lehman Bros. investment representative who pleaded guilty to money laundering charges in 2005, the Reuters news agency reported.

As part of the plea agreement, other drug-trafficking charges were dropped. Villanueva served six years in a Mexican prison for money laundering before his extradition to the U.S.

Villanueva was a member of the Institutional Revolutionary Party, or PRI, that held authoritarian control oo Mexico for seven decades, until it was ousted in 2000, and was often accused of working with drug traffickers. This year, the PRI will return to power with the election of Enrique Pena Nieto as president. He has said he will not make deals with traffickers.

Still, the Villanueva case reawakens the old ghosts of the PRI's past. In a statement, however, the PRI in Quintana Roo said Villanueva's confession was "regrettable" but that it would not have an effect on the party today because the case was so old (link in Spanish). Villanueva served as governor from 1993 to 1999.