Toxicity in arms trafficking

   October 2008: The U.S. consulate in Monterrey, Mexico, is attacked; the gunmen tossed a grenade at the front door. Days later, the Mexican Army finds 20 more grenades.

   February 2006: ATF agents find a manufacturing plant of home-made hand grenades in Laredo, Texas. Ninety-one roughly shaped grenades are taken away.

   ATF's official position is that grenades mostly come from the Central American black market. Armies saw massive demobilizations after the civil wars in the late 1980s — men returning home, not all empty-handed, Newell said.

   Of course, like Alcantar's case, some people in Mexico believe they can buy those same grenades here in the United States. "Now, obviously, they came up here to buy them." Newell says.

   The cartels work both sides of the line, a detail that is at times forgotten in the politics of the border where law enforcement agencies are often limited, sometimes fractured.

   Nearly 7,000 gun stores exist along the Mexican border. ATF keeps about 200 agents in the same area, a beat that is 1,200 miles long. Inter-agency fights between Justice and Homeland Security departments only makes matters worse.

   Until this summer, the United States never had a strategy that addressed arms trafficking to Mexico, notes a recently published report by the Government Accountability Office, Congress's investigative branch. Individual agencies, specifically ATF and Immigration and Customs Enforcement, lack clear law enforcement roles.

   "It's kind of a turf issue," says Jess Ford, the GAO investigator who authored the report.

   "They claim they're working well together. But when we talked to guys in the field, we found that wasn't often the case."

Hills of Southern Arizona

   At times, the problems are so overwhelming along the border that local law enforcement intervenes; sheriff's departments immerse themselves in the relentless flood of northbound narcotics and migrants, southbound cash and guns. Pima County Sheriff's Deputy Vincent Lopez is part of the department's border crime unit.

   The hills leading into Pima County are cobwebbed with trails, migrants and drug mules mostly, but also rip-off gangs, spotters glassing the cops from craggy stone outcrops.

   "Weapons are hard to find," Lopez says, standing over the shredded burlap remains of some mule's burden of weed. "There's no model, no rhyme to it."

   There is one consistency, he says. "With the guns, what goes south comes back up north."

Back in Santa Ana

   A deep drone as a truck laden with produce slows, then passes through the intersection of the two highways, turning left, heading for the United States. A faceless federale in a black and white Dodge Charger watches from behind his mirrored sunglasses. The dry wind stirs dust, then a whirling spinner that blows west before it collapses.

   A woman who lives next door to the Beltrán's address answers the door. She doesn't know her neighbors, she says.

   Be careful with your questions, she says. This place has changed.

   Michel Marizco is an organized crime reporter in Arizona and northern Mexico. He runs the news and intelligence Web site, BorderReporter.com, in Tucson. He can be reached at marizco@borderreporter.com