Valdez Cárdenas worked as a reporter for the national TV station,
joined the Sinaloa-based newspaper Noroeste.
a correspondent for the Mexico City-daily newspaper La Jornada.

founded Ríodoce. – Sinaloa, considered one of Mexico’s most violent states.

Valdez Cárdenas’ work is being continued by Forbidden Stories and the German newspaper Zeit online.

Valdez Cárdenas was also the author of several books on drug trafficking, including Miss Narco, which chronicles the lives of the girlfriends and wives of drug lords, and Los morros del narco: Niños y jóvenes en el narcotráfico mexicano (“The Kids of the Drug Trade: Children and teenagers in Mexican drug trafficking”).

In September 2009, Ríodoce published a series on drug trafficking entitled “Hitman: Confession of an Assassin in Ciudad Juárez.” One morning a few days after the conclusion of the series, a grenade was thrown into Ríodoce’s office, damaging the building but causing no injuries. The attackers were never identified.

On May 15, 2017, Valdez Cárdenas was shot 12 times and killed by unidentified gunmen around noon, blocks away from the Ríodoce offices in Culiacán, Sinaloa when he was 50 years old. The murder was condemned by the U.S. embassy in Mexico, the United Nations, and the European Union. A memorial to Cardenas was made in the Uncensored Library with his work available to be read.