Mexico City (CNN) -- As state authorities in Mexico asked federal prosecutors to take over the case of a 14-year-old accused of working as a drug-cartel hit man, the head of a children's rights organization criticized authorities' handling of the teen's detention.
Martin Perez, director of Mexico's Children's Rights Network, said late Friday that authorities should not have given television cameras and newspaper photographers access to the 14-year-old after his capture Thursday night.
"It was completely inappropriate, the form of presenting him in front of the media," he said.
"Everyone has the right to be presumed innocent, and also, it could put his life at serious risk. We have to remember that this is a fight between criminal organizations," he said.
Earlier Friday, Morelos state Gov. Marco Adame called on federal prosecutors to take over the case, according to a statement released by the state government.
Adame told reporters that he had asked for an inquiry into the teen's migratory status after preliminary reports indicated that the 14-year-old was carrying a birth certificate issued in San Diego, California, when authorities detained him and two of his sisters at an airport in central Mexico.
A spokeswoman for the Mexican attorney general's office said authorities detained the 14-year-old Thursday evening on suspicion of working as a drug-cartel hit man, but declined to provide details.
An anonymous phone tip alerted authorities that the teen was at the airport and heading to Tijuana, Mexico, the state-run Notimex news agency reported.
Citing unnamed military sources, Notimex said that the teen told authorities that he was a member of the Pacifico Sur cartel and had killed four people under orders from its leader. He also said he was a U.S. citizen and was under the influence of drugs when he carried out the crimes, according to Notimex.
A U.S. State Department spokesperson said Saturday that the boy's identity and citizenship are still being determined.
Sylvia Longmire, a former U.S. Air Force officer and senior intelligence analyst specializing in Latin America and Mexico's drug war, said Mexican drug lords often use young children.
"We've known for some time that Mexican-hired assassins were getting younger, but the story of a 14-year-old getting involved in this grisly business still carries some shock value," Longmire said.
"This won't be the last time we hear stories of young children picking up arms and killing people because it pays, and because they think it's cool," she said.
CNN's Rey Rodriguez, Nick Valencia and Krupskaia Alis contributed to this report.