An off-duty US Marine of Mexican descent was kidnapped last month along with his father and an uncle in crime-ridden northeastern Mexico, a local official told AFP late Thursday.
Gunmen kidnapped the three men on May 15, while the marine was visiting a family ranch located near a bridge over the Rio Grande connecting Mexico to the Texas border town of Brownsville.
"We have received a request from the FBI, and yes, we are working on trying to find Armando Torres III, a member of the US military," an official with the prosecutors office in the state of Tamaulipas told AFP, speaking on condition of anonymity.
Torres, a marine reservist, had crossed the border to visit his Mexican father, the official said.
Mexican media reported that Torres's relatives had approached the US consulate in Matamoros seeking help.
Mexico's far northeastern state of Tamaulipas has one of the highest rates of violence in the country.
Two of the Mexico's most powerful drug gangs, the Zetas and the Gulf cartel, are battling for control of lucrative border smuggling routes into the United States. Both groups have also branched out into other crime like kidnapping and extortion.
Some 70,000 people were killed in Mexico during the presidency of Felipe Calderon (2006-2012) due to drug related violence and the government crackdown aimed at stamping it out.
The current administration of President Enrique Pena Nieto has not released data on drug violence victims, but the crackdown has remained in place across the country.