Critics of Felipe Calderon, Mexico's president, and his so-called war on drugs have alleged that the Mexican government may be favouring the Sinaloa cartel, one of the country's most powerful drug-trafficking organisations.
Calderon's military-focused strategy has so far yielded little apparent result in a conflict estimated to have cost more than 15,000 lives since 2006.
Accusations of a "corrupt" Mexican government protecting certain cartels have been around since the 1970s, but now some of the country's leading investigative reporters say they have solid evidence showing that authorties are going after other cartels, but not targeting Sinaloa.
"There are no important detentions of Sinaloa cartel members," Diego Osorno, an investigative journalist and the author of a book on the Sinaloa cartel published last year, told Al Jazeera's Franc Contreras.
"But the government is hunting down [Sinaloa's] adversary groups - [and] new players in the world of drug trafficking."
The government did recently annouce the arrests of two members of the Sinaloa cartel, but experts say the men arrested were not senior cartel leaders.
Edgardo Buscaglia, a leading law professor in Mexico and an international organised crime expert, has analysed 50,000 drug-related arrest documents dating back to 2003, and said that only a tiny fraction of the them were against Sinaloa members, and low-key ones at that.
"Law enforcement shows you objectively that the federal government has been hitting the weakest organised crime groups in Mexico. The Familia Michoacana, mainly, Tijuana, Ciudad Juarez," he told Al Jazeera.
"But they have not been hitting the main organised crime group, the Sinaloa Federation, that is responsible for 45 per cent of the drug trade in this country."
Joaquin "El Chapo" Guzman - one of the most wanted criminals in the world - runs the Sinaloa cartel. Arrested in Guatemala in the 1990s and transferred to a maximum security prison in Mexico, Guzman escaped in 2001 and has amassed a more than $1bn forture by trafficking cocaine, heroine and methamphetamines to the US.
The Mexican government has consistently denied any involvement with Guzman and his cartel, backed up the US drug enforcement agency, which is involved in counternarcotics operations there.
Source: Al Jazeera