Those of you who watched the early episodes of CSI Las Vegas may remember Grissom staring at the crime scene and then saying, “How did you die? Talk to me.” His partner would then explain to the startled officers—and the viewers at home—that the scene “talked” to Grissom and helped him solve the crime. Everyone thought Grissom’s behavior was funny, made just for TV. While Grissom may have gone about things in a quirky way, he was actually pointing out something that is true: crime scenes can talk to you. In this article, I’ll explain how to use careful observation to get the crime scene to talk to you about the crime. Quoting Sherlock Holmes in The Memoirs of Sherlock Holmes by Arthur Conan Doyle, “You see but you do not observe.”

To begin with, you have to realize that a crime scene is really an accumulation of things that, when taken together and analyzed, tell the story of the crime. But in order to understand that story, you first need to find and collect all of the evidence. Here’s where careful observation comes in. Everyone’s first instinct is to ignore the big picture and head directly to the body or the central area where the crime occurred. But that kind of tunnel vision can lead you to misread the case. And if you just rush in, you risk contaminating or destroying crucial evidence. After all, the suspect had to get in and out of the scene somehow. Chances are, he or she left some evidence behind. If you pay attention, you can find that evidence.

Therefore, when you first arrive at a crime scene, you should always stop and carefully observe the entire scene before you do anything else. Once you’ve made your observations, then you can begin processing the scene. Of course, before you enter the scene, make sure you put on booties and gloves, and remember to change them when necessary. These are key steps both for protecting evidence that belongs at the scene and for preventing improper evidence from being added to the scene.

In some cases, the evidence will be right out in the open. You might see a lot of blood, overturned furniture, a weapon, etc. near the victim or in the central area of the crime. But you still have to make sure that your search is thorough; otherwise, you might miss something important. For example, I worked a case a number of years ago in which a woman was killed with a butcher knife. We collected over 200 blood samples. Out of all of those samples, only four of them didn’t match the victim. It turned out that she had cut the suspect during the struggle. When he received treatment at a local hospital, we matched his blood to our sample. That’s how we made our case. If we hadn’t conducted an exhaustive search of the scene, we might have missed the sample that led to the suspect.