Mexican and US investigators have begun excavating mass graves discovered in two ranches along the US-Mexico border after a tip-off by a protected witness who admitted his role in some of the killings.
The joint operation late on Monday evening, carried out by Mexican police and army troops working with FBI and Drug Enforcement Agency agents, immediately uncovered the bodies of two DEA agents who went missing last week, but investigators also found the remains of dozens more people nearby. No bodies were taken away from the ranch, said one witness, but soldiers left carrying large sacks.
Mexican security officials refused to confirm how many bodies had been found, while forensic experts estimated that it would take a month to complete exhumation work.
In a radio interview yesterday morning, Mexico's Attorney General, Mr Jorge Madrazo, said that two more ranches in the same area were being examined for bodies.
About 208 people have been kidnapped and "disappeared" in Juarez since 1995, many seized on US soil, by gunmen linked to the Juarez drug cartel. The cartel was led by Amado Carrillo Fuentes, alias the lord of the skies, until his death at the hands of a plastic surgeon last year. The cartel is now allegedly run by his brother, Vicente Carrillo Fuentes, currently in hiding and wanted by the FBI.
A six-month-old baby and three adults who claimed to be minding the ranch were detained at the scene of the crime, on the Casas Grandes highway, several miles from the US border. A fourth man apparently escaped during the operation.
Citizen groups in Juarez pressured the Mexican government into launching a serious investigation into the disappearances, which included people with no connection to organised crime, but little progress was made. Last January, Mr Madrazo acknowledged the infiltration of drug-traffickers in a special unit set up to investigate the disappearances.
The US-based informer who led the authorities to the mass graves is a former Mexican policeman. He said that some of the killings were carried out by federal policemen who worked as hired assassins for drug gangs in Juarez. The area is one of the main gateways for cocaine and other drugs shipped north through Mexico into the US.
Human rights organisations have repeatedly claimed that many of the victims were last seen in the hands of Mexican police, who have been accused of complicity with the cartel. State police were reported not to have been aware of the border operation in advance.
The list of disappeared people includes 18 US citizens, six Mexican soldiers, business people and former police agents, accused of informing on drug-traffickers.
The Mexican authorities have yet to announce official figures for the number of corpses found on the farms, sealed off by hundreds of Mexican troops. A team of forensic experts is waiting in El Paso to receive and examine bodies recovered in the investigation.
The owner of the ranch where the biggest grave was found is reported to be Mr Jorge Ortiz, whose father, former director of Mexico's Federal Security Directorate, was assassinated nearby in 1996.
Mexican authorities have played down the expanding influence of five principal drug cartels which operate along the country's US, Guatemala and Belizean border.
Investigators found a "narco-tunnel" running underground between the US and Mexico close to Juarez in 1993, through which traffickers planned to ship tonnes of cocaine via a disused factory on the Texas side of the border.