San Diego, California - Over the course of the last four days, members of the San Diego Tunnel Task Force, in collaboration with their enforcement counterparts in Mexico, have uncovered two sophisticated smuggling tunnels connecting commercial buildings in San Diego's Otay Mesa industrial park with warehouses in neighboring Tijuana, Mexico.

The first tunnel, approximately 600 yards in length, was discovered Tuesday evening based on evidence developed during a five-month probe by the task force. The passageway – equipped with lighting, a crude rail system and wooden trusses – exits inside a warehouse at 10145 Via de la Amistad. The entrance is accessed down a 70-foot shaft secured by a cement cover. The builders had installed a pulley system at the tunnel's U.S. entrance to hoist contraband up into the warehouse. The warehouse itself was filled with a variety of children's toys, including plastic three-wheelers, and boxes of televisions, similar to the merchandise found in the warehouse linked to the smuggling tunnel uncovered locally in October 2013.

Wednesday, task force investigators arrested a 73-year-old Chula Vista woman for allegedly overseeing the logistics at the Via de la Amistad warehouse. She is charged in a criminal complaint with conspiring with others to maintain a drug involved premises. The U.S. Attorney's Office for the Southern District of California is prosecuting the case.

"Here we are again, foiling cartel plans to sneak millions of dollars of illegal drugs through secret passageways that cost millions of dollars to build," said U.S. Attorney Laura Duffy. "Going underground is not a good business plan. We have promised to locate these super tunnels and keep powerful drug cartels from taking their business underground and out of sight, and once again, we have delivered on that promise."

The second tunnel was detected Thursday morning as investigators from Mexico, in close coordination with special agents from U.S. Immigration and Customs Enforcement's (ICE) Homeland Security Investigations (HSI), tracked leads related to the passageway uncovered Tuesday. The second passageway, which originates inside a warehouse located at 10005 Marconi Drive, is the more sophisticated of the two. Stretching for more than 700 yards, it is equipped with a multi-tiered electric rail system and an array of ventilation equipment.

"The discovery of these tunnels reaffirms yet again the vigilance and tenacity of our multi-agency task force," said Derek Benner, special agent in charge of HSI San Diego. "While technology certainly plays a part in our ongoing efforts, ultimately these investigations often owe more to the powers of observation and old fashioned detective work – and that was exactly what happened here."

The two tunnels are the sixth and seventh cross-border passageways discovered in the San Diego area in less than four years. If laid end-to-end, the seven tunnels would extend a distance of nearly two miles.

"Once again, the Tunnel Task Force has eliminated a multi-million dollar drug smuggling venture and have reduced it to nothing more than a colossal waste of money on the part of the drug cartels," said Drug Enforcement Administration (DEA) San Diego Special Agent in Charge William Sherman. "Our goal is to not only shut these tunnels down before they become operational, but to ensure that the cartels backing these elaborate smuggling operations are investigated and prosecuted."

The ongoing investigations into the two tunnels are being conducted by the agencies that make up the San Diego Tunnel Task Force, including HSI; U.S. Customs and Border Protection (CBP) - Border Patrol; the DEA; and the U.S. Attorney's Office. Additional support for this investigation has been provided by CBP's Office of Field Operations.

"These discoveries are a clear example of what solid police work and collaboration can do to disrupt the efforts of criminal organizations," said San Diego Sector Border Patrol Chief Patrol Agent Paul Beeson. "We are not going away and will continue our efforts to investigate, interdict and arrest those who try and circumvent the border in this manner."

While no contraband has yet been recovered in connection with these most recent tunnels, in the last four years authorities have seized more than 100 tons of narcotics associated with San Diego-area smuggling tunnels. Since 2006, federal authorities have detected at least 80 cross-border smuggling tunnels, most of them in California and Arizona.