Updated

Mexico's government allowed a group of undercover U.S. anti-drug agents and their Colombian informant to launder millions in cash for a powerful Mexican drug trafficker and his Colombian cocaine supplier, according to documents made public Monday.

The Mexican magazine Emeequis published portions of documents that describe how Drug Enforcement Administration agents, a Colombian trafficker-turned-informant and Mexican federal police officers in 2007 infiltrated the Beltran Leyva drug cartel and a cell of money launderers for Colombia's Valle del Norte cartel in Mexico.

The group of officials conducted at least 15 wire transfers to banks in the United States, Canada and China and smuggled and laundered about $2.5 million in the United States. They lost track of much of that money.

In his testimony, the DEA agent in charge of the operation says DEA agents posing as pilots flew at least one shipment of cocaine from Ecuador to Madrid through a Dallas airport.

The documents are part of an extradition order against Harold Mauricio Poveda-Ortega, a Colombian arrested in Mexico in 2010 on charges of supplying cocaine to Arturo Beltran Leyva. A year earlier, Beltran Leyva was killed in a shootout with Mexican marines in the city of Cuernavaca, south of Mexico City.

The documents show Mexico approved Poveda-Ortega's extradition to the United States in May, but neither Mexican nor U.S. authorities would confirm whether he has been extradited.

U.S. and Mexican officials did not respond to requests for comment.

The documents offer rare glimpses into the way U.S. anti-drug agents are operating in Mexico, an often sensitive subject in a country touchy about national sovereignty.

On one occasion, the informant who began working for the DEA in 2003 after a drug arrest met with the girlfriend of a Colombian drug trafficker in Dallas and offered to move cocaine for their group around the world for $1,000 per kilo. In a follow-up meeting, the informant introduced the woman to a DEA agent posing as a pilot. The woman is identified as the girlfriend of Horley Rengifo Pareja, who was detained in 2007 accused of laundering money and drug trafficking.

Another scene described the informant negotiating a deal to move a cocaine shipment from Ecuador to Spain and minutes later being taken to a house where he met with Arturo Beltran Leyva.

Beltran Leyva was once a top lieutenant for the Sinaloa drug cartel, led by Joaquin "El Chapo" Guzman. But he split from the cartel shortly after his brother was arrested in 2008, setting off a bloody battle between the former allies.

Fractured cartels have led to an increase of drug violence in Mexico. According to several counts more than 45,000 people have been killed since late 2006, though the government stopped giving figures on drug war dead when the toll hit nearly 35,000 a year ago.

On Monday, police in western Mexico found the bodies of 13 men at a gas station in the state of Michoacan.

The bodies were dumped near a convenience store on the gas station lot in the town of Zitacuaro, said Michoacan state prosecutors spokesman Jonathan Arredondo.

Arredondo said threatening messages were found with the bodies, but he wouldn't comment on their content or give any other details.

The western state is home base to The Knights Templar cartel, which like its predecessor, La Familia, is a pseudo-religious gang specializing in methamphetamine production, drug smuggling, extortion and other crimes.