I was solving the puzzle on the inside of a Pearl Beer bottlecap the other night, an old black and white Sherlock Holmes movie playing in the background, when something one of the characters said started nagging at me. Eventually I asked myself, "Self, just what can you tell about someone from his tracks?"
"Well," says I, "you can tell a helluva lot - starting from how tall he is to whether or not he's lying to you."
Don't hate me because I like Pearl Beer.
I digress. What's the gender of your subject? How tall is he? Is he carrying a lot of weight on his back?
Tracks are clues, the most clues a perpetrator will leave behind. One every thirty inches or so and as conclusive as finterprints. - Sherlock Holmes
Let's look at height. I’m not saying you can get an exact measurement down to the half-inch like a physician might take, but you can certainly get in the general vicinity. By and large, with most adults, the length of a complete footprint, measured in inches is about twice a person's height. Don't believe me? Try it. If you measure a 12 inch footprint, toe to heel, the person who made it is going to be pretty close to 6 feet tall. I measured the footprints of an entire infantry squad a couple of years ago, and with one exception this method of estimation held true.
Now, that one exception is an apt demonstration of why I emphasized adult earlier. Juveniles, particularly juvenile males, will rarely fit this profile. This is because of incomplete post-pubescent growth. If you've got a teenage son you know what I mean. He's 13, maybe 14, with these huge (typically stinky) flipper feet at the end of his legs that make him look like Ronald McDonald. Juvenile females aren't quite as problematic, but measuring their prints and determining a height can still be problematic.
Footprints are generally not used sufficiently by investigators of crime. Experience is needed... Once the eye has become accustomed to observe minute details a composite picture of interesting facts will stand out very clearly... - Modern Criminal Investigations, Söderman/O'Connell, 1940
Physical ailments or disabilities are another, more obvious example of what can be learned. Does the person walk with a limp, or is there a shuffle in their gait that translates as a longer, shallower toe drag?
You can often tell the physical condition of a subject with regard to intoxicants or medical condition. Do the tracks portray someone that's staggering or walking with a purposeful stride? Is there an overall continuity of direction and intent, or do the prints move aimlessly about and change course for no discernable reason? What about they say about the individual's response to the terrain? Do they avoid obstacles or change course suddenly, far after a typical person would do? Perhaps they have to reverse course, or change direction at the last minute - this could mean the person is dazed, inebriated, or unfamiliar with the area. Any one of those attributes could be important to putting a suspect at the scene of a crime, eliminating them from the suspect pool or even just accounting for their actions.
Sherlock Holmes: These two set of footprints lead to the alcove, where we shall find a lady of high breeding, accompanied by a gentleman with a pronounced limp.
Dr. Watson: Astounding, Holmes!
Sherlock Holmes: Hmm... Eileen Adler and Sir Reginald Mustry. This is a surprise.
Eileen Adler: Happy Birthday, Sherlock.
Sir Reginald Mustry: Remarkable, Holmes! I injured my ankle just yesterday.
- Sherlock Holmes' Surprise Party, Saturday Night Live
In Falkirk, Scotland, in 1937, a thief was discovered inside a shop in his stocking feet. He'd left his shoes outside by the drainpipe he'd climbed to get inside. There having been two previous, similar robberies as yet unresolved, police consulted a pathologist named Sir Sydney Smith and asked if he could determine whether footwear found abandoned at the previous scenes had been worn by the same man - he advised that they were, and explained how, including his observation that the right and left shoes showed signs of different and unequal wear, which led him to believe the suspect had a deformity in his left leg.