Mexico City (CNN) -- The U.S. State Department backed away Tuesday from earlier statements that a 14-year-old boy accused of being a drug cartel hit man in Mexico is a U.S. citizen.
Department spokeswoman Gini Staab said Monday the department had "confirmed the boy's U.S. citizenship," but took it back on Tuesday. Staab could not say why the department had pulled back the confirmation.
The boy had at least one consular visit Tuesday, another State Department official said.
The teen -- reportedly carrying a birth certificate issued in San Diego, California -- and two of his sisters were detained Thursday at an airport in central Mexico after an anonymous tip alerted authorities he was heading to Tijuana, Mexico, local media reported.
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.
But the boy faced a battery of questions from reporters after he was detained, answering questions point-blank as camera flashes lit his face.
"I slit their throats," he said, describing what he said was the killing of four people.
CNN's Claudia Dominguez, Rey Rodriguez, Nick Valencia and Krupskaia Alis contributed to this report.