The Tamaulipas state police are accused of murder, abuse of power and making false statements.
Twelve police officers have been arrested in Mexico following the discovery of 19 charred corpses near the U.S. border, Tamaulipas Attorney General, Irving Barrios, said on Tuesday.
The Tamaulipas state police are accused of murder, abuse of power and making false statements.
The bodies were discovered on January 22 in a burned-out pickup truck next to other burned cars in the town of Santa Anita in north-eastern Mexico.
The people had been shot dead, according to media reports.
Among them, according to Barrios, were migrants from Guatemala.
Media had reported that almost all of the victims were Guatemalans.
Tens of thousands of Central Americans every month flee poverty and violence in their homeland to seek a better life in the U.S.
One of the four dead identified so far was a Mexican migrant smuggler, according to Mr Barrios.
The possible involvement of other police officers, as well as criminal groups smuggling Central American migrants into the U.S. and fighting for control of the region, is still under investigation, Barrios said.