Article published on the 2008-08-31 Latest update 2008-08-31 10:40 TU
Despite the right-wing president's crackdown on drug-trafficking and related crime, violence has spiked since he took power in 2006.
More people have been killed in the eight months of this year than in the whole of last year and rights groups have reported 400 kidnappings, compared to 438 in 2007. They claim that for every kidnapping reported two or three more take place.
The case that sparked Saturday's protests, which saw white-clad demonstrators light candles in the centre of Mexico City and many other towns, was that of teenager Fernando Marti, who was found dead even though his father had paid a ransom.
Police officers are reported to have been involved in the Marti kidnapping and one of the protesters' main demands is a clampdown on police corruption.
Fernanda Solis, who joined the demonstration with a picture of her son who was murdered three years ago, echoed that call when she talked to RFI's French service correspondent Patrice Gouy.
"I think the first thing that needs to be done is a clean-up of the police," she said. "Because everyone knows that they are the ones who commit the crimes. Even the chiefs are involved, because there's a lot of impunity, the law is not observed and there's corruption everywhere."
Advertising executive Dany Aneros told correspondent James Blears that men in police uniform kidnapped him and held him in an official building.
"I was just waiting outside a friend’s house in la Colonia Roma and finally these guys took me," he said.
Security experts say that 97 per cent of kidnappings go unpunished.
The Reforma daily newspaper said Saturday that this week had been the most violent since Caleron launched the crackdown. It said that there have been 167 murders, with 24 police officers among the victimes, and that 21 decapitated bodies have been found.