Crime Scene Investigation for Mystery Writers
Understanding CSI: Creating a Believable Crime Scene
In order to write a convincing crime scene, a writer must know the basics of investigation and how a crime scene is constructed.
When investigators arrive at a crime scene, their main goals are to secure and preserve the evidence. If careful measures are not taken, important evidence can be lost.
Who Investigates the Crime?
Police officers and a Paramedic unit are usually first to arrive at a crime scene. The officers are in charge of securing the scene. A yellow crime scene ribbon ropes off the area to bar observers from entering and contaminating evidence.
A Crime Scene Investigator (CSI) then takes charge of the entire crime scene. This investigator oversees the crime scene by making sure the evidence is properly collected and preserved by himself or members of a special Crime Scene Unit.
A Crime Scene Photographer and Crime Scene Technicians may also be used.
The Medical Examiner (M.E.) or coroner will take charge of the body. As soon as evidence is collected it will be removed to a morgue where an autopsy will be performed to determine the cause of death.
Detectives then use the collected evidence and information provided by the CSI to investigate the crime. Their job is to work outside the crime scene by interviewing witnesses and suspects.
The Initial Investigation
Investigators start with a walk-through where the entire crime scene is accessed as a whole. Photographs, measurements, and a rough sketch is made to preserve the scene for further study and possible reconstruction.
Before anything is moved, a Crime Scene Photographer goes through the entire area and documents the scene with photos. He starts with taking wide shots of the scene, then close-ups of every bit of evidence as it is found.
Gathering Evidence
As soon as photos are taken, Crime Scene Technicians get to work bagging and tagging evidence to deliver to the crime lab. Investigators often wear disposable jumpsuits, booties, masks and rubber gloves to keep from contaminating the scene. They collect and preserve every piece of evidence they can find, no matter how small or insignificant it may seem. Evidence containers are sealed, dated and marked with the case number.
Types of Evidence Collected
Fingerprints
A crime scene is dusted for fingerprints. Each individual has a unique fingerprint. Sweat, oil and dirt can cause distinctive marks to left behind, which powder and chemicals can make visible. If a print can be found at the scene, it can be an important method for identifying a suspect.
DNA
DNA is a kind of molecule which is found in every cell. DNA can be lifted from blood, hair, skin, tissue, or fingernails. In order to be used as evidence, DNA found at the scene has to be matched to a suspect’s DNA. If a suspect has been injured and has left traces of blood at the scene of the crime, this can be detected through DNA matching.
Hair and Fibers
Strands of hair and fibers left at a crime scene can be important clues. They are carefully collected for examination. Certain fabrics, such as cotton or wool are easily identified. Artificial fibers can be broken down by chemical composition by the use of infrared spectrometry.
Firearms and Ballistics
if a gun is found on the scene, the investigator will make notes of the name, model and serial number of the gun and the type of bullets used.
A GSR (gunshot Residue Kit) may be used to check for traces of gunpowder on the victim’s hands. The victim will also be fingerprinted and bags placed over the hands to preserve any trace evidence.
Collected evidence is then taken to the lab for further study.
To read more about crime scenes and crime scene management:
Click here for an article on : Forensics for Mystery Writers
To read about female forensic authors click: Female Forensic Sleuths
Crime Scene Investigation
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