Writers and readers should never underestimate a talented investigator’s ability to read a crime scene. On the other hand, they can only “read” what exists. I should note as well that in large departments, detectives or investigators may not arrive at the scene for several hours or even before the body is removed.
Here’s just a short list of things they might look for at the scene of a murder:
- Signs of forced entry
- Signs of struggle
- Activities of the victim before the crime
- Activities of the perpetrator both before and after the crime
- Location, position, and state of the body
- Missing, added, and out-of-place objects
- Bullet trajectory
- Blood location, trajectory, and characteristics
- Observation of environmental conditions
- Elements of overkill
- Evidence of murder weapon
In addition to the scene itself, investigators gather information such as the last time the victim was seen or spoken to, the last time mail was taken in, anything seen or heard by neighbors or passersby, and the habits of the victim. This information is merged with the information at the crime scene to form a more complete picture. The two sets of information need to be compared and discrepancies reconciled.
The initial theory of what occurred may suggest looking for particular types of evidence or locations to search for fingerprints, DNA, shell casings, stray bullets, and possible trace evidence.
The activities of the perpetrator before and after the crime, such as attempts to clean up the scene, him/herself, posing the body, staging, preparing or eating food or lingering at the scene, and any signs of odd behavior all help police develop information about their suspect, both physically and psychologically. These details are critical to any investigation and provide the framework that police hope will be fleshed out with forensics. This is also a great place to give your reader an obscure clue or a red herring.
The location of the crime and the lifestyle of the victim also give police useable information. A murder that occurs in a suburban home is quite different from one that occurs in a downtown alley in terms of what evidence is visible to the naked eye (and how much evidence must be sifted through and ruled out).
Careful observation and recording of all elements of the crime scene are so important that technology was developed to “map” the scene with a laser in order to recreate it digitally. However, smaller police departments still need to rely on dozens of photos, measurements, sketches, and written notes.
Some investigators will return to the crime scene several times (or more commonly, the photos, reconstruction, or notes). The more experienced and intuitive the investigator is, the more this is helpful. Regardless, it is one of the tenets of investigation that, when you get stuck, you once again begin at the beginning, examining the scene. ViCAP (Violent Criminal Apprehension System), though it has some issues, is also an option for investigators if they suspect the perpetrator has committed similar crimes or they run out of leads.
It is only when there is so little obvious information at the crime scene that cases might hinge purely on what can be uncovered by forensic science. Developing a suspect is more difficult if the victim has been left somewhere other than where he or she was murdered (at a “dump site”), but it’s still possible to gain insight and clues.
Forensics may uncover leads not visible to the naked eye, but the fact remains that the impressions of the investigators at the scene remains the base component of any file. It is also vital information for behavior analysis, or profiling.
Next time, we’ll look at one of the oldest forensic techniques: Fingerprints.