Among the musicians killed in the past year, it isn't certain that their lyrics landed them in trouble. One of the best-known singers, Sergio Gomez, who led the group K-Paz de la Sierra, was killed after a concert in the state of Michoacan in December, but was best-known for his romantic ballads. Observers say some musicians may have been victims of domestic disputes or even caught up in drug trafficking themselves.
Still, a trend – real or perceived – has chilled artists.
More than a dozen have been killed in the past two years, and that's only the singers who make the news. In 2006, Valentin Elizalde was killed after his song, "To All My Enemies," became a hit. Jesus Rey David Alfaro, known as "El Gallito," was killed in Tijuana in February.
While have been around since the Mexican Revolution, drug traffickers didn't become the music's heroes until half a century later. Calls for censorship came almost immediately, at least since the release of the 1970s song "Contraband and Betrayal" by Los Tigres del Norte, says Elijah Wald, author of "Narcocorrido: A Journey Into the Music of Drugs, Guns, and Guerrillas." In recent years, politicians have called for restrictions and radio bans.