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In San Diego, federal authorities are trying a new tactic to find drug-smuggling tunnels near the border. They discovered two tunnels just last month, and seized 50 tons of marijuana.
As Amy Isackson reports from member station KPBS, authorities are now going door-to-door, asking for help.
AMY ISACKSON: Were in Otay Mesa, about four blocks from the U.S.-Mexico border. There are about 600 generic-looking warehouses in the area. Federal authorities plan to visit them all.
This Immigration and Customs Enforcement agent introduces himself to a warehouse owner.
(Soundbite of a knock)
RYAN(ph): My name is Ryan. Im a special agent with ICE, and Im here with members from the San Diego Tunnel Task Force. We're basically just ...
ISACKSON: This agent asked not to be named for security reasons.
RYAN: I don't know if you know this or not, but Otay Mesa is a real hotbed area for subterranean tunnels, drug tunnels.
ISACKSON: The two tunnels authorities unearthed last month were a few blocks from here. They were sophisticated - with electricity and ventilation - and they weren't the first.
Back in 2006, authorities discovered the longest tunnel ever, a mile and a half. All of these passageways surfaced in warehouses nearby.
Now, ICE is asking people who work in these warehouses to be on the lookout for...
RYAN: Things like subterranean noises, or jackhammering without a visible road crew. Or there's no construction going on, but you're hearing construction.
ISACKSON: Agents ask to take a look around. There are hundreds of boxes bound for Carl's Jr. restaurants in Mexico.
Mr. GABRIEL ANDRADE (Immigration and Customs Enforcement Agent): That's toys for kids' meals; this is cheese.
ISACKSON: Gabriel Andrade manages the operation. He says he never suspected a thing when he'd drive by one of the buildings where they found a tunnel last month.
Mr. ANDRADE: I think it is very hard to know. There is a lot of traffic of the trucks, and we don't know - and hear nothing.
ISACKSON: Andrade says it's also difficult to see anything. He says, for example, the neighbors keep their doors closed all day. That piques agents' interest, and we go next door.
(Soundbite of forklift)
ISACKSON: A forklift unloads boxes of chicken taquitos to be sent to U.S. grocery stores. Margarito Calleja is the manager here. He says they keep the doors down to keep the sun off the food.
Mr. MARGARITO CALLEJA (Warehouse Manager): (Foreign language spoken) (Through Translator) Really, we don't communicate with people at other warehouses. You arrive; you go inside; you do your work. You leave at 6 in the afternoon. Adios. Bye-bye.
ISACKSON: There's constant commotion in this area. It's a few blocks from the commercial border crossing.
Joe Garcia, with Immigration and Customs Enforcement, says that's part of why tunnelers like the area.
Mr. JOE GARCIA (Immigration and Customs Enforcement Agent): You have shipping and distribution going on, almost around the clock now. There's a lot of truck traffic. It's a perfect cover for them.
ISACKSON: And that's the case for the tunnel found on Thanksgiving, in a corner of this empty warehouse.
(Soundbite of walking down steps of a ladder)
ISACKSON: I'm going down a ladder into the tunnel here. It's starting to smell humid already. And so we're in.
Unidentified Man #1 (Immigration and Customs Enforcement Agent): It's approximately 2,200 feet from here to Mexico.
ISACKSON: This tunnel began in the kitchen floor of a home in Tijuana. Agents think it took 220 days to dig.
Unidentified Man #1: Right here you can see the jackhammer lines where the tunnel diggers, you know, jackhammered out this clay.
ISACKSON: We walk, crouched over, until we come to a steep drop.
Unidentified Man #1: Are you all right?
ISACKSON: The tunnel plunges 90 feet. Smugglers laid tracks at the bottom, and used a cart to ferry the drugs. ICE's Joe Garcia says it's impossible to know how many tunnels are under the border.
Mr. GARCIA: The only thing that stops it from being Swiss cheese is that it costs a lot of money to do these. I'd be naive to say now, we've got them all. It's done. We're over.
ISACKSON: Garcia says it'd also be naive not to enlist Otay Mesa business owners in the hunt.
For NPR news, I'm Amy Isackson in San Diego.
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