Divers on Wednesday recovered the remains of two of the six workers missing since the crumbling bridge tossed them into the water
Officials said drug traffickers purchased a plot of land for $240,000 and spent an additional $86,000 to build a house on the land to conceal smuggling activity.
The tunnel began in an restaurant in Mexacali, Mexico called El Cerape, and ended in the three-bedroom home in Calexico, California.
Officials say the traffickers began using the tunnel in February to transport narcotics, without realising they were being monitored by US drug agents the entire time.
On Wednesday, they announced that they had seized nearly 1400 pounds of marijuana and arrested four people in the US.