Story highlights U.S. Customs and Border Protection facilitates the teen's return

Mexican officials say they'd been working to rehabilitate Edgar Jimenez Lugo

An aunt in San Antonio signed off on the teen's repatriation there, an official says

The U.S. citizen was found guilty of torturing and beheading at least four people

Mexican authorities set free a former teen cartel hit man on Tuesday and sent him back to the United States.

The release of Edgar Jimenez Lugo, a U.S. citizen known as "El Ponchis" or "The Cloak," comes less than three years after a Mexican court found him guilty of torturing and beheading at least four people and kidnapping three others as an operative for the South Pacific Cartel.

The teenager's age -- 14 at the time -- and his on-camera description of the slayings, brought international attention to the case. Analysts said the dramatic example showed how Mexican drug gangs were increasingly recruiting youths.

On Tuesday, Mexican authorities said he had served his three-year sentence and had been sent back to the United States.

The teen, now 17, boarded a commercial flight from Mexico City to San Antonio, Texas, on Tuesday morning, according to Jorge Messeguer, government secretary in Mexico's Morelos state.

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Asked about the teen's case, a U.S. Customs and Border Protection spokeswoman said the agency facilitated the return of a U.S. citizen on Tuesday. She declined to provide details, citing privacy restrictions.

An aunt in San Antonio signed off on the teen's repatriation there, a state official in Morelos told CNNMexico

A judge released him five days early, Messeguer said, to steer clear of too much publicity in the high-profile case.

"The judge determined she wanted to guarantee his privacy and safety," he said.

After the teen's arrest in 2010, some children's rights advocates were critical of Mexican authorities who paraded him before television cameras and allowed him to answer reporters' questions.

The teen answered the battery of questions, point-blank, as camera flashbulbs flickered. Troops standing beside him wore masks to hide their faces. But the teen's face was clearly visible.

"I slit their throats," he said, describing what he said was the killing of four people.

With his hands shoved into the pockets of his cargo pants, the teen told reporters he was paid weekly in dollars and pesos. But in answering questions about whether he knew what he was doing when he allegedly participated in the killings, the teen said he was under the influence of drugs and unaware of his actions.

The teen told reporters a cartel leader threatened him.

"I either work or he'll kill me," he said.

On Tuesday, Mexican officials said they had been working with the teen to rehabilitate him.

"We did not wait until two weeks before his exit to work with him. We have been working with him all this time on the therapeutic aspect, and saw results. But we cannot assure that it is a complete rehabilitation, because the time to work with him was limited," said Ana Virinia Perez Guemes, president of a court for adolescents in Morelos. "Really, the three years of imprisonment are not enough to achieve a complete reintegration."

Perez said the teen would continue rehabilitation in the United States.

"We think that we did the best we could with him, and the idea is that he can expect to have a better life in a different country, in his country of origin, when he gets the support that he needs, in an environment of understanding and of boundaries, and not of discrimination, where they can help him to return to a productive life," she told reporters, according to Mexico's state-run Notimex news agency.

Rosalia Martinez de Leon, another judicial official, stressed that the teen was no longer serving time.

"He is a minor who is requesting a return to his country of origin, and so ... he is owed all the due protection so that he can find the best place to continue," she said.