Reporting from Mexico City — A law enforcement official investigating this week's massacre of 72 migrants in northern Mexico was missing Friday, while possible car bomb explosions rocked a television station and police station in the same violence-torn state.
Meanwhile, authorities in Tamaulipas state said they had so far identified the remains of 31 of the massacre victims and determined that they were from Honduras, El Salvador, Guatemala and Brazil.
Tamaulipas officials said Roberto Suarez, an agent for the state prosecutor's office involved in the investigation, went missing Wednesday. That was a day after Mexican marines found the slain migrants on a ranch outside the town of San Fernando.
A San Fernando police officer was also reported missing Friday. The case is now run by the federal attorney general's office.
The disappearances and car blasts appeared to be further signs of the lawlessness that prevails in Tamaulipas, a stronghold of drug traffickers across the border from Texas.
In Ciudad Victoria, the state capital, a car blew up shortly after midnight outside the Televisa office, though it was not immediately known whether it was rigged with a bomb. The explosion caused damage but no one was hurt.
Less than an hour later, a second car exploded outside a San Fernando police station. No one was injured.
The car blasts were the second and third in Tamaulipas this month. A car detonated outside state police headquarters in Ciudad Victoria three weeks ago.
Last month, a car bomb blast in Ciudad Juarez, in the border state of Chihuahua, killed a police officer and three others, raising worries that drug gangs were adopting a new weapon in the nearly 4-year-old drug war.
In recent days, attackers have hurled grenades at Televisa stations in Tamaulipas and neighboring Nuevo Leon state. Drug gangs have made it so dangerous to report the news that many outlets have stopped trying.
In San Fernando, Mexican authorities and foreign emissaries worked to identify massacre victims found Tuesday after a survivor from Ecuador made his way to a highway checkpoint manned by marines.
Officials said the migrants were captured on their way to the U.S. border by the Zetas gang. Alejandro Poire, spokesman for the Mexican government's anti-crime strategy, said in a radio interview that the victims were killed because they refused to work for the drug-trafficking group, among the most bloodthirsty in the country.
The slayings touched off a fresh outcry by migrant rights activists who have long said that Mexico mistreats or fails to protect the estimated 400,000 workers who cross its territory on their way to the United States each year.
Migrants have for years been targeted by robbers, rapists and corrupt officials in league with smugglers. They face a new threat as drug traffickers increasingly move into people-smuggling or target migrants for extortion.
Mexican officials, sensitive to charges that they don't protect migrants at home while complaining of mistreatment of Mexicans on U.S. soil, say they are cracking down on the smugglers and kidnappers.
Cecilia Romero, head of the federal immigration agency, said authorities raided 16 safe houses in Tamaulipas last year, rescuing 812 foreign nationals. She said 30 immigration agents have been jailed and 300 fired for corruption. About 43,000 foreign migrants have been sent home this year.
"We are sorry we never found these 72," Romero said of the slain migrants. "Probably they were hidden in a trailer when transported, and we could not detect them. That is how it works. The migrants are invisible to us. They hide from us."
Romero later said that the Ecuadorean survivor, Luis Fredy Lala Pomavilla, has been offered a humanitarian visa to remain in Mexico if he chooses, the Associated Press reported.
Mexico's growing drug violence prompted the State Department on Friday to instruct U.S. diplomats in the northern city of Monterrey to remove their children from the area. The move came after a shootout near the American School Foundation last week.
Times staff writer Tracy Wilkinson contributed to this report.