WITNESS: Following a hit man's rifle to Mexico

Tim Gaynor is a Reuters correspondent based in Phoenix who covers immigration in the United States and writes about crime and security along the Mexico border. In the following story, he tells how he traced a Kalashnikov rifle bought in Arizona to a mining town in Mexico where it was used by a drug gang in a battle with police and troops that killed 23 people.

By Tim Gaynor

PHOENIX (Reuters) - The agent raised the machine gun to his shoulder and let rip a deafening hail of shots that smacked through a bullet proof vest, punched holes in a car door and spat up a plume of sand in the levee behind.

Taking the plugs out of my ringing ears, I walked over the gritty desert firing range to look at the damage from the Kalashnikov.

The traffic of guns of this type from the United States to the warring Mexican drug cartels is the less-reported flip side of the drugs trade north from Mexico and South America.

I have covered crime on the U.S.-Mexico border for several years, and was trying to grasp first hand the devastating power of the weapons used in Mexican crime, the ease with which they are trafficked over the border, and the human cost for the Mexican authorities so often in the firing line.

"This is the type of fire power that we are seeing being trafficked into Mexico and arming the cartels," said Tom Mangan, a senior ATF special agent with the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives, examining the debris from the firing and explaining the effects.

Last year, Mexican cartels murdered more than 2,500 people in an all-out war for lucrative drug routes to the United States worth billions of dollars. Many were shot using assault rifles readily and legally available in the United States, and trafficked to Mexico, where gun sales are banned.

THE CANANEA SLAUGHTER