Joel Hardin can tell a lot about a person by following his or her footsteps.

Or so he says. But you’ll have to take his word for it, Hardin says. Aside from a handful of people he has trained and still works with, there is nobody else in the world who is doing what he does.

The retired U.S. Border Patrol agent runs a private training and consulting business where he teaches tracking, goes on search-and-rescue missions, and consults with prosecutors and defense lawyers as an expert in criminal cases.

Hardin says a good tracker—or “sign cutter,” as he prefers—can determine a person’s size, shape, height, weight and carriage by the “signs” he or she leaves behind when moving through an area: footprints, scuff marks and the way light reflects off a particular surface.

And that’s just for starters. A good tracker can usually tell whether the person being tracked is used to walking or is familiar with his or her surroundings, Hardin says. An experienced tracker who follows a trail long enough may be able to draw “very definite and accurate” conclusions about that person’s frame of mind, personality, background, intentions, even nationality.

Hardin apparently is so good at what he does he can tell whether a child he is tracking is approaching a stranger or someone familiar, whether a person he’s following is excited or dreads the prospect of going to work, whether he’s tracking a “normal” 15-year-old or one with the mind of a 5-year-old.

Hardin once claimed he could tell that a murder suspect was a young Mexican male by the way the suspect maneuvered his way through a raspberry patch.

He still insists he can tell the difference between an Asian and an American, or a “Westerner,” as he calls them, by the way an individual walks, unless the Asian has been fully assimilated into the Western world.

Westerners “always have somewhere to go and are always in a big hurry to get there.” They tend to take longer strides with more pronounced heel strikes than Asians, who typically take shorter steps and “put their feet down more flatly” than Westerners, Hardin cheerfully explains.

“The fact of the matter is people from different countries walk differently,” says Hardin, who says his conclusion is based on a lifetime of observing people and is borne out by scientific research showing that certain people have a more pronounced “heel-toe” way of walking than others.

Now 70, Hardin spent 25 years with the Border Patrol, where he says he first discovered his “special expertise” in tracking, often as a consultant to law enforcement on criminal investigations and missing persons cases. He helped in the hunt for the Green River serial killer and the search for convicted Soviet spy Christopher Boyce after Boyce escaped from a federal prison in 1980.