Authorities said Villanueva was shot multiple times by an unknown "commando" in the commercial center of Monterrey, the economic capital of north Mexico.
She was known for defending high profile defendants accused of drug smuggling, including, most recently, regional police chief Javier Herrera Valles, who was jailed for his alleged links to drug cartels.
The cartels are believed to be responsible for some 12 other murders since Saturday night in Mexico's border region with the United States, including in Ciudad Juarez, where authorities discovered a male victim with his head and genitals severed.
The border town is among the most violent in all of Mexico, despite the deployment of 8,500 troops in the city of about 1.5 million, with some 2,800 people murdered in 2008 and 2009 in drug-related incidents in the city.
Across Mexico, around 9,600 people have died in drug-related violence since the start of 2008, despite a military clampdown ordered by Calderon involving some 40,000 troops deployed across the country.
The gruesome violence between drug cartels vying for control of lucrative smuggling routes into the United States will be a key topic for Obama, Calderon and Harper as they meet for a trilateral summit in Guadalajara.
Crime, including murders and kidnappings, related to Mexico's drug gangs has spread north, posing security threats to the United States and Canada, and both countries are expected to offer Calderon additional assistance in his struggle to contain the cartels.
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She was known for defending high profile defendants accused of drug smuggling, including, most recently, regional police chief Javier Herrera Valles, who was jailed for his alleged links to drug cartels.
The cartels are believed to be responsible for some 12 other murders since Saturday night in Mexico's border region with the United States, including in Ciudad Juarez, where authorities discovered a male victim with his head and genitals severed.
The border town is among the most violent in all of Mexico, despite the deployment of 8,500 troops in the city of about 1.5 million, with some 2,800 people murdered in 2008 and 2009 in drug-related incidents in the city.
Across Mexico, around 9,600 people have died in drug-related violence since the start of 2008, despite a military clampdown ordered by Calderon involving some 40,000 troops deployed across the country.
The gruesome violence between drug cartels vying for control of lucrative smuggling routes into the United States will be a key topic for Obama, Calderon and Harper as they meet for a trilateral summit in Guadalajara.
Crime, including murders and kidnappings, related to Mexico's drug gangs has spread north, posing security threats to the United States and Canada, and both countries are expected to offer Calderon additional assistance in his struggle to contain the cartels.
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