The navy said in a statement late Tuesday that troops helped transport two suspects, one of them wounded in a clash with police in a suburb of Monterrey, to a hospital on Sunday. There, it said, custody was handed over to the police chief of the city, Santa Catarina.
TV news footage from that day showed Jose Marquez Compean surrounded by troops and in the custody of soldiers. His beaten body was found wrapped in a blanket in the nearby city of San Nicolas de los Garza on Monday.
Marquez Compean's wife, Hilda Rodriguez, told Milenio Television on Tuesday that she had identified her husband's body and seen images of his arrest.
“I saw him in the news, how they put him in a patrol and then a helicopter, and then he turns up dead,” Rodriguez sobbed. “Why did they kill him? Who killed him? I want justice. I have three children.” Alejandro Garza y Garza, attorney general of Nuevo Leon state, where Santa Catarina is located, told Milenio the police officers who made the arrest are being investigated.
No arrests have been made.
Santa Catarina security chief Rene Castillo said he had no knowledge whatsoever of the case.
“I don't know anything, I don't know anything, I don't know anything. That's my position,” Castillo told The Associated Press.
Marquez Compean and two others were arrested Sunday by Santa Catarina police officers who were part of a convoy carrying Castillo on official business.
The convoy was later attacked by gunmen in an apparent attempt to free the suspects. Two of the security chief's bodyguards were killed, and four other people wounded.
The metropolitan area of Monterrey, Mexico's third-largest city, has been gripped by escalating violence between drug cartels and security forces.
President Felipe Calderon has deployed tens of thousands of soldiers and federal police across Mexico over three years in a US-backed campaign to crush brutal cartels battling each other for trafficking and drug-dealing turf.
Gang violence has since surged, claiming nearly 18,000 lives.
Also Tuesday, jet planes loaded with 450 federal police officers arrived in Ciudad Juarez to bolster a federal force struggling to control drug violence in the border city known as Mexico's murder capital.
The surge boosted the number of federal agents there to 3,500 and came on the same day that US Secretary of State Hillary Rodham Clinton and top-level security officials met with Mexico's leaders and pledged to help tackle the problem.
More than 2,600 people were killed last year in Ciudad Juarez, a city of 1.3 million across the border from El Paso, Texas. At least 500 people have died this year.
The violence is not limited to the border: In Veracruz, a southern port city on the Gulf of Mexico, a naval officer and a civilian died Tuesday during a pre-dawn shootout with gunmen who sped through a military checkpoint, military officials said in a statement.
One man was arrested at the scene, and 10 guns and a hand grenade were seized, the officials said.
Also Tuesday, gunmen barged into a motorcycle store in Tuxtepec in the southern state of Oaxaca and killed four people, officials said.
In the northern border city of Tijuana, meanwhile, the police department announced Tuesday that it will switch its focus from battling drug traffickers to fighting common street crime.
Residents of the city have complained in recent months that police are ignoring home burglaries, car thefts and muggings, focusing instead on disrupting traffickers fighting over routes leading into San Diego, California.
Soldiers sent by the government will continue to fight the cartels, state prosecutor Rommel Moreno Manjarrez told reporters.
Brutal cartel-related crime has declined so far this year in Tijuana, but common crime is up 40 percent.
