In 1993, after Colombian drug lord Pablo Escobar was killed, Mexican trafficker Amado Carrillo Fuentes brokered deals with the Cali and the Medellín cartels, replacing Escobar as the most powerful cocaine smuggler in Latin America. Carrillo Fuentes grew his empire with the help of Joaquín “El Chapo” Guzmán and the Beltrán Leyva brothers. Together they expanded retail distribution to every region of the US, pioneered the large-scale production of crystal meth, and cultivated relationships with elite Mexican bankers who helped them launder millions of dollars.

As the riches grew, so did the government’s greed. According to Hernández, in the 1990s Mexican officials instituted a fresh fundraising strategy: “No more ‘paying taxes’: now you had to offer hefty bribes, enough to make the fortunes of politicians and businessmen overnight.” From then on, she suggests, it was only a matter of time before the drug lords began to consider corrupt officials part of their personal staff. As one former cartel member explained, “The traffickers pay for the campaigns, and then get protection when their guys are elected.”

In 1997, after Carrillo Fuentes died (or, some say, faked his death), his empire fractured into smaller groups. Then in 2001, shortly after El Chapo escaped from prison, more than 25 major traffickers merged into a nationwide group known as The Federation, with El Chapo at the helm. Hernández’ most incendiary argument is that presidents Vicente Fox and Felipe Calderón essentially worked for El Chapo. Their “war on drugs,” she argues, was a front for The Federation’s hostile takeover of the Tijuana Cartel and its attempt to expand its territory by attacking the paramilitary cartel known as Los Zetas. “In previous epochs,” she writes, “none of the cartels would have dared to declare war on another, nor would any government have allowed it.” But Fox, Calderón, and their ministers not only sanctioned the war, she alleges, they used police and intelligence agents to support El Chapo’s agenda.

Here, as in many areas of this provocative history, Hernández’ evidence is largely circumstantial. She points, for example, to the inexplicable personal fortune of Calderón’s director of the “war on drugs,” Genaro García Luna (worth some $2.8 million in 2010), as well as to a study by economist Edgardo Buscaglia, which found that only 1.8 percent of the organized-crime arrests in Mexico from 2006 through 2010 were of people connected to El Chapo’s cartel. She also provides details about officials who have been tried for corruption, about drug trials that have turned into farces, and about honest anti-drug officials who have been reassigned.

But what Hernández reads as corruption may simply be the ugly business of realpolitik. As Buscaglia himself points out in Narcoland, even American anti-drug agencies “think that it’s always more feasible to control a single, consolidated organization, rather than hundreds of atoms that don’t really hook up, producing a situation of chaos and instability.” Policies that favor one cartel over another don’t necessarily mean that the Mexican presidency is beholden to a particular narco.

Whether or not Hernández is accurate about all the dirty details, her diagnosis that much of Mexico is now run by cartels is undeniable. Anyone who doubts it should read Martínez’ gripping work of travel reportage, The Beast.

In style and substance, the two books could not be more different. An accomplished investigative journalist who entered the field after her father was kidnapped and murdered in 2000, Hernández analyzes scores of criminal trials and recently declassified documents, fleshing out details with interviews of a few highly placed anonymous sources. Her writing is uneven but her research is impressive, and she has put her life in permanent peril by focusing on Mexican presidents and their top ministers, as well as the leaders of Mexico’s most powerful cartels.

The Beast is less interested in narcos than Central American migrants who traverse Mexico in hopes of reaching the United States. A reporter for the online newspaper, Martínez is a powerful storyteller and his approach to investigative journalism is closer to anthropological immersion: He walks with migrants through bloody forests, eats with them at spartan shelters, and rides with them atop speeding trains.

Marcela Valdes is a freelance writer who specializes in Latin American literature and culture.