His music videos painted a vivid portrait of street life in Mexico in all of its gritty detail: chained dogs and flashing knives, drug paraphernalia and boasts of violence. He rapped around a posse of unsmiling men, their shirts off, tattooed, flashing hand signals and glaring — “los casi muertos” he said, pointing at them with his thumbs: the nearly dead.

“This is my hell,” he rapped.

And officials in Mexico said this week that the songs of Christian Omar Palma Gutierrez, the rapper known as Qba, were more than just a performative fantasy.

Gutierrez has been arrested in connection with the horrific deaths of three film students after investigators said that he confessed to dissolving their bodies in acid as part of his work with a notorious drug cartel, according to news reports.

The murders of the three students, Javier Salomón Aceves Gastélum, 25, and Marco García Francisco Ávalos and Jesús Daniel Díaz, both 20, have shocked Mexico, which is coming off a record year of violence. The three disappeared while working on a school project in the western state of Jalisco, and officials now say they were killed after unwittingly filming at a property connected to a rival group to the powerful gang that Gutierrez is believed to have worked for, the Cartel Jalisco New Generation. One other person has been arrested, and six other arrest warrants have been issued.

The Associated Press reported that sources close to the investigation said Gutierrez worked as a “cook” for the cartel, dissolving corpses in water tanks full of acid and later disposing of the liquefied material, for an income of 3,000 pesos a week, about $160. Chief investigator Lizette Torres told Agence France-Presse that Gutierrez has participated in three other murders, and prosecutors have been scouring his videos as part of the investigation. He has confessed to dissolving the students’ bodies in acid, news agencies reported.

As a rapper, Gutierrez was no basement amateur. His videos, seemingly professionally made, garnered millions of views on YouTube and earned him as much as $300 per month. He was scheduled to perform Sunday at a music festival in the border outpost of Tijuana.

But he is now in protective custody in jail after confessing to the authorities, raising concerns about the danger he faces from the cartel, the AP reported.

Gutierrez seemed to understand the treacherous stakes of the life he lived. In a music video set in a cemetery, he raps about his own death, reckoning with the “very bad” things he’s done.

“If tomorrow I’m not here,” he sings, “I want to tell you how much I regret all that I did, all that I said. Mom, dad, forgive me; I couldn’t escape the darkness.”

The tragic fate of the students of the Universidad de Medios Audiovisuales in Guadalajara, Jalisco’s capital, has been met with vociferous protests, in the media and in the streets, and denouncements by public officials, including President Enrique Peña Nieto. An estimated 12,000 people marched through the streets of Guadalajara on Thursday carrying signs and chanting, “Not one more; we want peace!” and “It’s not three; it’s all of us.”

Some, including El Universal newspaper columnist Luis Cárdenas, said they saw the tragedy reflected in Gutierrez’s life as well, in a country where fears continue about the pull of a ruthless cycle of violence for residents of its poorer sectors.

“Omar thus dissolved the film students, with whom, curiously, he might have had many things in common,” Cárdenas wrote in a piece titled, “The hit man was singing, nobody heard.”

“What would have been his destiny if luck had placed him elsewhere? I am sure that his talent would have brought him very far, he sings well and it’s clear that his videos tell a story, like the stories told by those that study film, maybe other circumstances would have made him a happy man, because precisely that, the unhappiness, that is what Omar masterfully reflects in his musical work: the bitterness of a canceled future, the life in a hell of which there is no other option but to kill or die.”

“Sismo” Garduno, a producer who worked with Gutierrez told the AP that the rapper, who had a young son, “had dreams of growing, of making a living from this, so his parents wouldn’t have to struggle anymore, so his family could get ahead.”

Garduno told the AP that American gang styles were popular among young people in Mexico.

“My experience in this genre is that a lot of them want to feel very ‘cholo,’ ” Garduno said.

Mexico is coming off the deadliest year in its modern history with 25,300 homicides. Jalisco, too, had a record year of violence, with 1,369 murders. The New Generation cartel is considered one of the country’s most powerful, making headlines after shooting down an army helicopter, ambushing police officers and attempting to intimidate a former attorney general by sending him a pig’s head.

Officials speculated that the students may have been misidentified as members of a rival gang. As they left an area where they had filmed, their car broke down, and six armed men dressed as law enforcement officers approached them and ordered them onto the ground. The students were driven to a house; one was beaten to death, and officials believe the other two were executed because of that.

The head of the country’s human rights commission, Luis Raúl González Perez, told the AP that “what we have to do is to stop this climate of violence, because there is the risk that if there are no jobs, no education, if the young people don’t have recreational opportunities, well, the drug cartels are going to recruit them.”

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