A sea of white-clad demonstrators carrying candles filled the 2½-mile route between the Mexico City's Angel of Independence monument and the main Zocalo square. The government estimated the crowd at 50,000 shortly after the march began, but thousands continued to pour into the streets. Thousands more marched in other cities across the country.
Romana Quintera, 72, wore a photograph of her baby grandson who was kidnapped for ransom five years ago when gunmen burst into her home and killed her niece. Two people have been imprisoned for the attack, but they have refused to reveal the boy's fate, and Quintera said investigators have given up on the case.
"We're desperate. We've been fighting for five years. We want an answer," she said, holding back tears. "We ask authorities with all our heart to be more sensitive. Maybe nothing like this has happened to them, or they would be more sensitive."
Despite the arrest of several drug kingpins, little has improved the ground since the Calderon government began its crackdown. Homicides have surged as drug cartels battle each other for control of trafficking routes and stage vicious attacks against police nearly each day. In the gang-plagued border state of Chihuahua alone, there have been more than 800 killings this year, double the number during the same period last year.
This week, a dozen headless bodies were found in the Yucatan Peninsula, home to Mexico's most popular beach resort, Cancun. Saturday's protests were inspired by the abduction and murder of the 14-year-old son of a wealthy businessman. The case provoked an outcry when prosecutors said a police detective was a key participant in the abduction for ransom.
The boy's father, Alejandro Marti, called on top government officials to quit if they could not stem the crime wave. His challenge became a rally cry at the march, where many held up signs with his words: "If you can't, resign."
The first to arrive for the protest was the family of 24-year-old Monica Alejandrina Ramirez, who was kidnapped on in 2004 and has not been heard from since.
Hours before the march began, the family stood silently beneath the independence monument, holding up large banners with her picture. Some colleagues of her mother, a circus performer, walked on stilts and wore clown wigs to help draw attention.
"The most frustrating thing has been the indolence of many of the authorities, their insensitivity," said her father, Manuel Ramirez Juarez, a family doctor. Having staked his presidency on improving security, Calderon responded to the rising anger by summoning governors and mayors to a national security meeting, drawing up a a 74-point anti-crime plan.
It included plans for better police recruiting and oversight systems, as well as an anti-kidnapping strategy within six months. The Defense Department promised to equip police with more powerful automatic weapons.
"This a cancer that we are going to eradicate," Calderon promised during a televised address Monday. But he urged patience, warning that rooting out drug gangs and bringing security to the streets would not happen by decree.
Neither will cleaning up and bolstering Mexico's police.
In some northern towns, officers complain of having to share guns, and many have quit in terror after seeing colleagues killed in front of their homes.
More than half of Mexico's state and municipal police officers have only a primary education, making it difficult for them to aspire to the highest ranks and salaries. Many are tempted to join the payrolls of criminal gangs.