The contraband is stuck to cars' undersides with magnets

The fifth case so far this year of a so-called "blind mule" was discovered on Thursday, February 28, in the Xicoténcatl Leyva Mortera neighborhood of Tijuana, police said in a press release.

The term "blind mule" takes its name from a tactic used by smugglers who place packages of drugs underneath vehicles — unbeknownst to the vehicles' owners — that cross the border from Mexico into the U.S.

At about 7:45 a.m., police received an emergency call from a resident on Adolfo López Mateos Avenue asking for help after discovering that five suspicious packages had been stuck to the chassis of his car with magnets, police said.

"The blocks, of different sizes, contained a green, dry herb similar to marijuana, and each one weighed about 9.5 kilograms [almost 21 pounds each]," the police statement said.

The car's owner told police that he works in the U.S. and parks his car overnight on a public street. He said that, based on previous alerts from police, he regularly checks under his car to make sure there are no drugs.

Police officials used the discovery to issue a new alert to the public, warning those who cross frequently from Tijuana to San Diego to carefully check their vehicles before making the trip.

According to the police statement, 17 such cases were reported in 2012.