An American was found among the 193 corpses recovered in April in mass graves in Mexico near the U.S. border, a U.S. official said Tuesday.

Mexican authorities identified the remains of an American in San Fernando, a town 85 miles from the border with Brownsville, Texas, and alerted the U.S. State Department, said a State Department official who declined to be named because he was not authorized to speak on the record.

The official did not identify the victim because the family has not authorized it.

Mexican officials said many of the victims buried in the mass graves in San Fernando were migrants heading to the U.S. who were kidnapped off passengers buses, killed and buried by the Zetas drug cartel.

The U.S. consulate in Matamoros, across the border from Brownsville, released a message when the graves were being unearthed saying the consulate had received three reports from U.S. citizens or their families regarding buses being boarded by criminals.

"In at least one instance, male bus passengers, including an American citizen, were forcibly removed from those buses and have yet to be located," the message said. It is not known whether the U.S. citizen the consulate reported missing was the one found in one of the 47 pits excavated.

So far, the Mexican government has charged 73 suspects in the killings, including several police officers who allegedly aided the Zetas gang. Not all have been arrested.

Authorities said the Zetas gang, a vicious drug-trafficking organization, sometimes forcefully recruits migrants to fight their rival, the Gulf cartel.