In cargo pants and a T-shirt, the skinny, American-born 14-year-old looked like he should be in middle school. Instead, he was surrounded by three armed Mexican soldiers in ski masks and camouflage as he told journalists that he helped a Mexican drug gang behead four people.

Mexican officials say they arrested the youth known as “El Ponchis” late Thursday at an airport south of Mexico City with a 19-year-old sister who is accused of helping him dump the bodies. Authorities said he was caught with two cell phones that held photographs of tortured victims.

Many youth have been used by drug cartels in their bloody battles against the government and each other, but the story of El Ponchis may be the most shocking.

Authorities said the siblings were detained at an airport near Cuernavaca in Morelos state with paid tickets to flee the country.

The boy's sister said they were headed for Tijuana, where they planned to cross the border and seek refuge with their stepmother in San Diego.

More In: International | News