Edgar Quintero, standing, and his band, BuKnas de Culiacan, write commissioned songs glorifying Mexico’s drug lords. (Shaul Schwarz) Edgar Quintero, standing, and his band, BuKnas de Culiacan, write commissioned songs glorifying Mexico’s drug lords. (Shaul Schwarz)

Every business needs good publicity: a commercial during the Super Bowl, a celebrity endorsement, a viral video — or maybe a specially commissioned song about your awesome car, your favorite gun and how many limbs you severed with your trusty machete.

The documentary “Narco Cultura,” which opens Friday, looks at the music genre of narcocorrido and rising superstar Edgar Quintero and his band, BuKnas de Culiacan. If you don’t understand the Spanish lyrics, the music seems happy and bouncy — you wouldn’t know you’ve been tapping your foot to a song about gruesome, real-life drug violence along the U.S.-Mexican border.

The overarching irony of the film is that Quintero is a mic for hire — writing songs about the exploits of cutthroat traffickers — who lives a tidy life in a house in L.A. with his son and his wife.

“He is searching for an immigrant identity, and this is what he dumps into,” says the film’s director, Shaul Schwarz. “He has a need in a strange way to connect with his heritage through this bizarre genre.”

It’s easy to assume that narcocorrido is to contemporary Mexican music as gangsta rap is to mainstream American hip-hop, but Schwarz sees flaws in that comparison. “Clearly both genres … glorify some sort of crime,” he says, “but if you look at gangsta rap, they were rhyming about their struggles. You look at [narcocorridos] and they’re not rhyming about their struggle. They’re trying to interview the biggest narco they can and get every word approved by [him].”

Some of the documentary’s most chilling moments are interviews with teens from Juarez, Mexico, where drug-related crime is out of control. (The film also follows Juarez police investigator Richi Soto’s losing battle to stanch the bloodshed.) The kids talk about their favorite kingpins like they’re movie stars and sing along with the songs.

Schwarz doesn’t see a direct link from the music to a life of crime, but he wonders: “Will this music push people over the edge? If you’re the kid in Juarez and all the girls want to date a narco, are you more likely to do someone a little favor, and then you find yourself in this life?”

On the other hand, Schwarz is clear that narcocorrido isn’t the cause of the kids’ envy.

“If people are walking out [of the film] blaming the musicians, they’re hanging the messenger,” he says. “If I could choose what people would walk away with, it would really be, ‘How did we get to this point where the genre is happening in the first place?'”