Top police killed in Mexican assassination wave

One day after acting federal police chief Edgar Millan was brutally murdered, four gunmen in a truck shot and killed anti-kidnapping commander Esteban Robles, authorities said.

Robles was rushed to hospital after the attack Friday but did not survive.

The violence, believed to be mostly related to the government's stepped up fight against drug trafficking, saw a new grim chapter Thursday in Mexico City as gunmen ambushed Millan, 41, and assassinated him in his home.

"Mexico has lost one of its most valuable men, a security professional at the service of the nation," a statement from the Public Safety office read. A suspect was detained hours later.

The office of Mexico's president noted that Millan had played a key role in the anti-organized crime crackdown involving more than 36,000 military troops.

Since December 2006, President Felipe Calderon's federal government has deployed 36,000 military troops and thousands of police around the country in an operation aimed at clamping down on organized crime.

Officials claimed the rising death toll showed that criminals were panicking about the clampdown, and trying to cling to control of their narcotics distribution networks especially in northern states which border the United States.

Robles and Millan's killings were not the first of a senior anti-crime authority. Top federal organized crime investigator Roberto Velasco was gunned down at his home in the capital May 6. He died in hospital shortly thereafter.