Smell That? It’s Money

Smell That? It’s Money

By Anne Miller


Dollar bills have a faint but distinct odor. A new tool could help law enforcement sniff out smugglers’ megabucks that are illegally crossing borders.

By Anne Miller

Ah, the sweet smell of cold, hard cash.

That’s not just figurative language. Bills really do have an odor, which comes from the ink used in printing them as well as from whatever lingers as the money changes hands — food, dirt, cocaine. 

Sniffing out dollars has been a holy grail for law enforcement hot on the trail of drug trafficking and money laundering. An estimated $30 billion in U.S. cash crosses into Mexico each year thanks to smugglers in the drug trade. U.S. agents snagged only $106 million in the past fiscal year. Catching a whiff could halt serious crime.

Dogs do it. In 2012, Argentine pooches made headlines when the tax agency deployed them to sniff out capital flight. They trained their snouts on the smell of American-bill ink. One big find: $30,000 stashed inside the spare tire of a car heading to Uruguay via ferry.  

Soldiers during the day at stopped cars, inspecting them.

Soldiers inspect vehicles at a checkpoint on a highway in Tijuana, Mexico.

Source Corbis

In 2010, the Department of Homeland Security issued a challenge to private companies to design “a device that will search for and identify bulk quantities of currency — secreted on persons, in hand baggage and luggage, and/or in privately owned vehicles.”


Now, researchers at KWJ Engineering say they’ve hit upon it. Their Bulk Currency Detection System, or BCDS, will make like the dogs and suss out big bags of cash. It involves a miniature gas chromatograph-mass spectrometer, along with a handheld probe. It detects the unique “fingerprint” of bills, which is shed by volatile molecules on the surface. 

Say a little red sports car pulls up to the border crossing in Laredo. Officers pull the car over for a random search. If something in the car triggers concern, or if a police dog signals that there might be something funny in the trunk, officers could pull out a BCDS and run it over a bag in the back to determine whether it’s holding a big load of cash.

Researcher Suiqiong Li says the prototype remains two to three years away from production.

Conceivably, the new devices could do dogs one better — the official research poster presented at a recent conference even compared the device to man’s best friend. Over time, the cost of the dogs’ training and upkeep would vanish. Not a bad deal: Have you seen the price of kibble these days?

This story originally ran Aug. 19, 2014.