Zetas cartel chief busted

The alleged leader of the Zetas drug cartel - who is suspected of being the mastermind behind the rash of killings discovered over the past month in mass graves across the northern Mexican state of Tamaulipas, as well as the massacre last August of 72 Central American migrants - was captured on Saturday.

Martin Omar Estrada Luna, known as El Kilo, was arrested along with five other suspects near the main square in San Fernando, Tamaulipas, the navy said in a statement on Sunday. As many as 20 mass graves have been discovered over the past few weeks in San Fernando. It was also in this city where the massacre of Central Americans took place.

The body count from the pits had reached 145 as of Tuesday. Forensic experts are trying to determine the identities with the help of DNA provided by families who have reported their loved ones missing.

According to witnesses, gunmen have been stopping passenger buses across Tamaulipas and ordering men off. The Zetas are thought to be forcibly recruiting drug runners to smuggle narcotics into the United States.

On Monday, the Inter-American Commission on Human Rights condemned the 145 killings and called on the Mexican government "to clarify what has occurred, identify the victims, punish those responsible, and urgently adopt the necessary measures to ensure that such acts do not continue to happen."

More than 40 people have been arrested, including 16 police officers from San Fernando who have been put on administrative leave until the inquiry is over. The officers are thought to have been helping the Zetas cartel.

The Zetas began as a Mexican military unit that defected and began working with the Gulf cartel, based in Ciudad Juárez, Mexico, across the border from El Paso, Texas. The Zetas later split from the Gulf cartel and the two groups are now fierce rivals.

Officers death toll

In a related matter, a total of 470 officers from Mexico's military, navy and federal police forces lost their lives between January 1, 2000 and March 22 of this year in the ongoing drug war. Quoting official figures, the Mexico City daily El Universal reported Monday that more than half of the police and military casualties occurred in the country's six northernmost states, where rival gangs battle to control lucrative routes to the United States.

Michoacán, Chihuahua and Tamaulipas are considered the most violent states for law-enforcement officials, according to statistics complied by Mexico's public-safety office. Since President Felipe Calderón declared a war on the cartels in 2006, more than 30,000 people have died in the drug-related war.