After the discovery last week of a cross-border tunnel between Mexicali and Calexico in the Imperial Valley, officials are more convinced than ever that the drug- and people-smuggling business has gone underground, literally.
The tunnel was the 10th discovered in California and Arizona since federal officials tightened security at the border after the terrorist attacks of Sept. 11, 2001.
The 10 tunnels in two years compare to just 15 tunnels discovered in the previous 12 years. Officials say it's clearly a trend.
"Our goal is to stay two steps ahead of the smugglers and their criminal enterprises," said Lauren Mack, spokeswoman for the Bureau of Immigration and Customs Enforcement. "We're on to this tunnel activity."
The latest tunnel, discovered when a Border Patrol vehicle patrolling the border fence struck a sink hole, is 200 yards from a tunnel discovered in mid-September.
"The methods that smugglers use are becoming more and more sophisticated as our enforcement efforts are enhanced," said Ken Stitt, chief patrol agent with the Border Patrol.
Four Mexicans were arrested in September by Mexican authorities in connection to that tunnel. Believed to have ties to the violent Arellano Felix drug cartel, the four were sent to Mexico City for questioning; they remain in jail.
Officials said they are trying to determine whether the latest tunnel project is linked to the tunnel found in September.
Cross-border tunnels have been discovered from San Diego to Nogales, Ariz. Most of the tunnels, like the two in Calexico, are thought to have been discovered before they could be used by smugglers to bring either drugs or illegal immigrants into the United States.
But a tunnel discovered near Tecate, east of San Diego, was believed by authorities to have been in use for more than a decade to bring drugs into the United States and money and weapons to Mexico.
Both the U.S. and Mexican governments have vowed a crackdown on the tunnels and tunnel diggers. In the spring, after a tunnel was found near the San Ysidro port of entry, Mexican officials dispatched a special anti-tunnel squad from Mexico City.
The tunnel found Wednesday led from a tile company building in Mexicali to an open field in Calexico near a housing project. The tunnel, 15 feet below ground and several hundred yards long, followed a zig-zag route, had a crude lighting and ventilation system, and was shored up by wood pillars, much like the tunnel discovered in September, officials said.
After the discovery, Calexico city workers were assigned to excavate the tunnel, which was filled with water, possibly from runoff. Residents of a nearby housing development complained of being kept awake in recent weeks by the noise of heavy equipment.
"It was so bad, I couldn't sleep," said Maria Ramirez, a longtime Calexico resident. "I kept thinking: Why can't they do that work in the day?"