Updated

JIUTEPEC, Mexico -- U.S. Embassy officials met with Mexico's alleged child assassin to check on his welfare and provide him with information on a lawyer in the case that he is an American, a spokesman said Tuesday.

Mexican officials and his family say the boy, 14, who claims he carried out at least four executions, was born in the United States even though he spent much of his childhood in Mexico.

But Embassy spokesman Alexander Featherstone said his citizenship has not been determined, and U.S. officials met with the teen on Monday to offer him consular assistance "in case he is a U.S. citizen."

The boy, who authorities only named publicly as Edgar, was arrested Thursday with a 19-year-old sister, Elizabeth Jimenez Lugo, as they tried to board a plane to Tijuana in an airport near Cuernavaca south of Mexico City.

The two planned to cross the border into San Diego to be with their mother, Jimenez Lugo told reporters when they were handed over to federal authorities on Friday. Soldiers also detained another sister, Lina Erika Jimenez Lugo, 23, who had driven them to the airport.

Officials accuse the three of working for the Cartel of the South Pacific, a branch of the splintered Beltran Leyva gang fighting for control of the central state of Morelos, where he grew up.

Authorities say Edgar and Elizabeth Jimenez Lugo worked for Julio "El Negro" Padilla, who has been fighting for control of the drug trade in Morelos, formerly part of the territory under the Beltran Leyva gang, which broke up with the killing of leader Arturo Beltran Leyva by Mexican marines a year ago.

Elizabeth Jimenez Lugo was allegedly Padilla's girlfriend.

Mexico's Organized Crime Unit said late Monday it is holding the boy's sisters for 30 days for investigation of possible kidnapping and organized crime charges.

No birth certificate for the boy is on file in San Diego County. But birth records show Elizabeth Jimenez Lugo was born in 1991 at Mercy Hospital and Medical Center in San Diego, and her sister, Lina Erika, is registered as having been born in Jiutepec, Mexico. Both records name Carmen Solis, born in 1926, as the mother and no father.

Solis, who has since died, was their paternal grandmother who also raised Edgar in Jiutepec, according to a close relative who asked not to be named for fear of retaliation.

Authorities has been looking for Edgar since videos appeared a month ago on the Internet showing teenagers mugging with weapons and some victims, claiming they were drug cartel assassins. One teen nicknamed "El Ponchis" was believed to be as young as 12.

The relative said his nickname is "Ponchi," a name the family gave him when he was a pudgy 4-year-old.

Soldiers hunting for the boy barged into a baptism party of his young cousin in late November to search every corner. They returned two days later, nearly breaking down the gate to the two-story concrete house shared by several families in a working-class suburb of Cuernavaca, the relative said.

This time they even checked under the bed, but didn't find the boy.

After that, his family decided to send him with his sister to San Diego to be with their mother, the relative told The Associated Press.

"We didn't think he would get caught," he said.

The boy told reporters that he was kidnapped and forced to work for the cartel at age 11 and participated in at least four executions, though he said he was drugged and under threat.

When he was still a baby, Edgar's father brought the boy with five siblings from San Diego back to Jiutepec, an industrial suburb of Cuernavaca, to live Solis, the father's mother. The relative didn't say when she died.

"The boy loved her very much, and we watched how he would hug her as if she were his mother," the relative said.

Neighbors said the father remarried and the two captured teens talked about a stepmother.

The family knew the petite boy with curly hair and soft voice was hanging out with the wrong crowd but refuse to believe he was a killer for hire.

Ponchi was an errand boy, not an assassin, the relative said.

"He is a sweet boy," the relative said. "Maybe he appeared in the video just to show off."