A birth certificate proved that a boy with whom an American schoolteacher had sex is 13 years old, contradicting assertions from the woman's lawyers that he is older.
The certificate provided to The Associated Press by officer Alfredo Arenas Moreno showed the boy was born in January 1994 in Penjamo, Mexico.
"The document is real, recognized by the state government of Guanajuato, Mexico," Arenas said in an e-mail. Arenas, who heads the Baja California state police international liaison unit, said he got the certificate from the FBI.
The lawyer for 25-year-old Kelsey Peterson suggested earlier this week that the boy might be 16 or older - too old for a statutory rape charge to apply.
Peterson faces federal charges for crossing a border to have sex with a minor, which is punishable by 10 years to life in prison and a $250,000 (170,776 EUR) fine. A judge denied bail for her last week. She also faces state charges of kidnapping, child abuse and contributing to the delinquency of a minor.
The AP had previously named the boy as police searched for him but stopped using his name in reports after authorities charged Peterson with a sex crime.
Peterson fled Nebraska with the boy, a former student of hers, on Oct. 26. They were found by Arenas in a mall parking lot in the border town of Mexicali, Mexico, on Nov. 2.