Another marijuana tunnel and two more warehouses found

Federal authorities have unearthed another cross-border tunnel in a San Diego warehouse district, the second major tunnel discovery and multi-ton seizure of marijuana believed to be from Mexico’s most powerful drug cartel in a month.

The tunnel, which started in a residence in Tijuana, stretched nearly half a mile and split into two passageways, with the branches emerging at separate warehouses nearly 800 feet apart.

The tunnel was within a block of a subterranean passage found three weeks ago, where authorities seized more than 25 tons of marijuana, the second-largest marijuana seizure in U.S. history.

With Thursday’s haul of 20 more tons, authorities said they had dealt a significant double blow to Mexican organized crime groups. The amount seized was the equivalent of about 17 million marijuana joints, said Ralph Partridge, the special agent in charge of the Drug Enforcement Administration office in San Diego.

“This has a huge impact,” Partridge said.

Authorities believe the drugs found in the tunnels this month belonged to separate cells of the Sinaloa drug cartel, which has long used northern Baja California as staging ground for smuggling drugs into California. The discovery on Thursday morning came after U.S. agents stopped a tractor-trailer loaded with marijuana bales that had just left a warehouse on Marconi Drive.

Inside the empty warehouse space where a “For Rent” sign hung out front, agents found an opening cut into the concrete floor. They traversed the tunnel to the second opening in a warehouse a few blocks away on Via de la Amistad.

To find the opening on the Tijuana side, Mexican Army soldiers traversed the entire 2,200-foot passage, which featured lighting and ventilation systems. They surfaced in the kitchen of the residence where a family lived. Authorities said six people were arrested in Mexico.

“They were very surprised,” said Tim Durst, an assistant special agent from Immigration and Customs Enforcement who heads the multi-agency San Diego Tunnel Task Force. The bust culminated an eight-month investigation, built largely on tips from informants.

Authorities seized four tons of marijuana in the Tijuana residence and another location in Mexico; three tons in the tunnel; and about 13 tons in the tractor trailer. Two men were arrested in California, including the driver of the tractor-trailer.

The tunnel was one of the longest ever discovered and had several unique features that highlighted traffickers’ evolving approach to ferrying drugs under the border. The floor of the passageway was lined with tongue-and-groove wooden boards that served as a level surface for the cart and rail system. There was an underground room, roughly 10 by 20 feet, where smugglers off-loaded the marijuana bales from the cart before hoisting them to the surface.

The most unusual feature was the construction of two tunnel branches, which authorities speculate allowed smugglers alternate exit points in case of surveillance.

richard.marosi@latimes.com