The year was 1903, and Sir Arthur Conan Doyle had just published another Sherlock Holmes story: “The Adventure of the Norwood Builder.” It’s fun to read, but it certainly isn’t relevant to today’s police officers, right? After all, most modern forensic techniques hadn’t been discovered yet. Fingerprinting was brand new then and makes only one brief appearance in the story.
But maybe there’s something in the story for officers today. Let’s take a closer look.
The story is about a homicide, and for once the police were smarter than Holmes–or so they thought. Detective Lestrade, triumphant with the discovery of a bloody fingerprint on the wall, crows, “you must acknowledge that we have been a little in front of you this time, Mr. Holmes.”
Later, though, in a private moment with his friend Dr. Watson, Holmes says, “The fact is that there is one really serious flaw in this evidence to which our friend attaches so much importance.”
“Indeed, Holmes! What is it?”
“Only this: that I know that that mark was not there when I examined the hall yesterday.”
Gulp. At the end of the story Holmes once again finds the true killer. The thumbprint was a red herring, planted there to implicate the wrong man.
What’s the message for today’s officers? Here it is: Always document not just what you did, but what you found (or didn’t find). Writing “I looked for fingerprints” is meaningless unless you add “and found none.” Sometimes–as Holmes knew very well–what you don’t see is more important than what you do see. Write it down so that you’ll have evidence if you need it.