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Monday, October 7, 2013

Crime Scene 101 for Writers: Decisions. Decisions.


 (Photo credit: Wikipedia)
I just finished reading Mike Roche's book, THE BLUE MONSTER. It was a wonderful window into urban police investigation. One of the things that I appreciated about the book was understanding how individual competencies in processing a crime scene can make all of the difference in bringing a perpetrator to justice.

To this end, I thought that this week on the blog we could look at some decisions that writers can make and different points at which things can go well, or a writer could twist the plot.


STEP ONE -  Is it safe to go on the scene?

1. Do you have a hazardous environment called a HOT ZONE?
   A  Hot zones can be created by
       * natural disaster - such as Tsunamis in Japan, floods, fires, and storms
       * mass disasters - such as terrorism
       * crimes - like the anthrax filled envelopes through U.S. Postal Service
       * accidents
   B. Hot zones might include
      * nerve gas
      * radioactive materials
      * nuclear threat
      * chemicals creating toxic and/or combustible threats
      * bio-hazards such as pathogens, venom, and parasites along
         with other disease causing organisms

2. Is the bad guy still on the scene?

3. Did they plant booby-traps or bombs Link to bombs article

STEP TWO - Will the first response team get there in time?
* To save the victim(s)?
* To save the house?
* And in their attempts to preserve life and/or preserve property
   will they damage the evidence to
   make it harder to solve the crime?

STEP THREE - How effective will your First Responders be when they contain and secure the scene?

Soldiers of the United States Army Criminal In...
. (Photo credit: Wikipedia)

* Only someone with a good reason to be at the crime
   scene is allowed in the area - this precludes the media,
   the family, and PI's. In Janet Evanovich's books
   Stephanie Plum really can't just walk in and look
   around because she happens to be doing Morelli.
* Others who might contaminate your scene and
    twist your plot might include looters and bystanders
* An officer has to stand at the entrance of the scene
   and log in everyone who enters and exits the police
   tape including the precise times when they entered and
* Others who enter a crime scene can introduce
   Finger prints Link to finger print article
   Foot prints Link to footwear article
   DNA Link to DNA 101 article
   Tire prints

Now this might be a good place to talk about Locard's Exchange Principle:

Whenever someone moves throughout an environment there will be an exchange of materials.
* A person will pick up materials such as animal hair, dirt, and fibers and take them away with them.
* A person will leave trace evidence showing that they were there - fingerprints, hair strands, DNA from spit
   or blood.
* The longer that two people are in contact and the more intense their exchange the more trace evidence will
    be left in place.

Imposing Lokard's Theories there will be a transference. This is why any superfluous people need to be kept from the scene.
* When extra information is introduced it slows the process and creates extra work for the investigators
   because they have to sort through all of the data.

Another reason to keep others at a distance:
* Public access has to be restricted so that someone with a cellphone etc. won't be releasing information
   to the public.
* The police typically only release information that is critical to identifying the perpetrator.
* They keep the rest quiet so they can monitor the story.
   For example, in interrogation Link to Interrogation article a suspect lets slip a piece of information that
   only the perpetrator or someone who had seen the scene would know. This is a big piece of evidence
* This also helps prevent copy cat cases because the full MO has not been revealed. Maybe that's just what
   your plot needs.

A Crime Scene at the National Museum of Crime ...
A Crime Scene at the National Museum of Crime & Punishment (Photo credit: Wikipedia)

STEP FOUR : How competent are your investigators in gathering and processing evidence?

VIDEO QUICK STUDY (11:41) good overview poor sound quality.
VIDEO QUICK STUDY (25:52) A little long but this is the process from the military (US Army)

* Proper warrants are obtained (a property owner can give consent for searches)
* A search strategy is developed by the officer in charge
   This prevents the crime techs from damaging or overlooking evidence
   This usually happens before the investigators enter a scene. Everything must be considered even the spatial
   relationships of objects, blood spatter patterns etc.
* There are four main types of searches -
English: Footwear impressions left at a crime ...
English: Footwear impressions left at a crime scene. (Photo credit: Wikipedia)
   line search 
   circular (or spiral) search 
   serpentine search 
   funnel search
* Evidence is identified -
   1 Trace Evidence - (also called Micro-evidence)
      tiny pieces like sand, saliva, latent prints.
   2 Real Evidence  (also called Tangible Evidence
     and Macro Evidence)-  physical objects
      that inform a case or played a part in the incident.
 * Everything in the area is potential evidence
 * Assumptions are made prior to scientific analysis -
    Is it blood? Is it cocaine?
 * Field Tests are conducted (like blood swabs)
 * Pattern Evidence - Helps to understand the scene.
     This is protected with photography (digital and
      video) VIDEO QUICK STUDY (5:39)
   * Maps are created
   * Measurements of all pertinent pieces of evidence
      are documented.
   * All objects are measured from one set
      point called a datum. 
   *This is sometimes done with
     portable computerized mapping systems called
     Total Station Serving Systems
VIDEO QUICK STUDY  (9:51) excellent lecture on evidence collection. Shows process and equipment in use.
*Macro search
   1. hunt and peck
   2. flashlight
   3. alternate light Link to alternative light article go to
                         second half
   4. taping
* Micro Search
    1. vacuum
    2. fingerprinting
    3. using chemical solutions (such as BlueStar or Luminol)
    4. swabs

STEP FIVE - Did your responders process everything correctly so that it is useful in making a case and also permissible in court?

* Documentation
   `Crime Scene inventory list is created identifying each marker
   ` Chain of custody list
* Preservation
* Transportation of evidence

STEP SIX - The investigators hand the evidence over to the scientists and a whole new set of complications can twist your plot. Have fun!

See how this article influenced my plot lines in my novella MINE and my novel CHAOS IS COME AGAIN.

Thank you so much for stopping by. And thank you for your support. When you buy my books, you make it possible for me to continue to bring you helpful articles and keep ThrillWriting free and accessible to all.


  1. Interesting article, looking forward to the one on bullistics

    1. Did you see this when it went up?

  2. This is very useful. Thank you!

  3. This article is so good-it is a print, clip and keep. Thanks!

    1. I'm so glad you found it helpful!


  4. I like the style...explicit, step by step. Twas like a refresher course for me.