If you want to write a crime story with a forensics expert like Temperance Brennan or Kay Scarpetta, you're going to need familiarity with police protocol, the subsequent crime scene investigation and what a lab uses to process the evidence. Taking you from the crime scene to the lab, award-winning author Jennifer Chase shares her expertise on the subject.
What it Takes to Solve a Crime
From what we see on television, in the movies, and in some books, it seems relatively simple to solve a crime. Or, is it? Let’s break it down in three simple categories: crime, searching the crime scene, and comparing clues to find the perpetrator.
1. Importance of First Officer at the Crime Scene
The first police officer that arrives at a crime scene is the often the driving force behind a successful crime scene investigation. The crime scene locale is where most of the physical evidence associated with the crime is obtained. Evidence is located, documented, and collected.
The most important task for the first officer on the scene is to protect the integrity at the scene. That means ANYONE not directly related to the investigation should not be allowed to enter the area - ever. The perimeter should be cordoned off with crime scene tape, rope, or barricades. Anyone coming or going should be documented on a list. Evidence should be untouched and left for crime scene technicians or investigators.
While waiting for the investigating team to arrive, the first officer should always:
• Write down names of witnesses and anyone else at the scene. • Note who was at the scene when the officer arrived. • Establish the basic facts. • Keep ALL suspects and witnesses separated. • Instruct the witnesses not to discuss the events or compare notes. • Do not discuss the crime scene with witnesses or bystanders. • Listen – sometimes an officer can pick up subtle clues by being a good listener. • Protect evidence that might be in danger of being destroyed (weather poses a big problem for crime scenes). Sometimes, it’s important to expand the crime scene area as an added precaution.
2. Searching the Crime Scene
Cooperation. Dedication. Experience. Crime scene examination must be done in a careful and methodical manner. A crime scene is three dimensional, it’s imperative that it be looked at it from that perspective.
Body
Never move the body or position the body prior to the investigation. Each investigator should approach the body one at a time, not in a group. This helps to determine if it has been moved, altered, or staged. Take detailed notes of everything. Sketch what you see. Describe the clothing, condition, new or old wounds, defense wounds, position, signs of struggle, evidence, etc.
Photographs
Fingerprint Evidence
Fingerprint evidence is the most delicate evidence and should be searched, documented, and collected first. Weather and other environmental factors play an important role.
• Latent, visible, and molded or plastic prints can be found at or around the crime scene area. • Photograph the prints before lifting them. • Prints from other sources can also be found at the crime scene, such as wrist, palm, foot, and lip or ear prints.
Expanding the Search
Curious Onlookers at the Crime Scene
• Keep onlookers away from the scene in order to prevent contamination. • Keep detailed notes of evidence, make sure that outside onlookers didn’t leave anything that might be misconstrued as crime scene evidence. • Keep other officers out of the scene that aren’t working the area. • In large common areas, such as streets and walkways, cordoned off several areas for searches. • Make sure there is only one way in and out of the crime scene to make sure that it can’t be contaminated.
3. Comparing Forensic Evidence
From any crime show that we’ve viewed on television or in the movies, there is that moment where the evidence matches and the suspect is then brought to justice. They make it seem so easy and it only take a few moments. It’s definitely much more complicated than it looks and the forensic professionals who make that positive distinction are nothing less than exemplary in their work.
The microscope is the key piece of equipment in a forensic lab. It’s an optical instrument that uses a lens or a combination of lenses to magnify and resolve the fine details of a particular object of interest.
There are five main types of microscopes that are used most frequently in examining forensic evidence in crime scene investigations:
This microscope consists of a mechanical system that supports both the microscope and optical system. It illuminates the object and passes light through a series of lenses to form an image of the specific specimen as seen by the eye. There are a number of magnifying powers, such as 10x, 20x, 200x, or 450x.
Comparison Microscope
This is a common microscope used in forensic labs because it offers a side-by-side comparison of specimens. It’s basically two compound microscopes combined into one unit. The unique feature allows it to use a bridge incorporating a series of mirrors and lenses to join two independent objective lenses into a singe unit. This microscope is effective in comparing bullets, hair, and fibers.
Stereoscopic Microscope
This type of microscope is used to characterize the structures of physical evidence that do not necessarily need a high magnification. It’s generally in the magnification range of 10x to 125x. It gives a distinctive three-dimensional image of the object. It is no doubt the most commonly used microscope in the forensic lab.
Polarizing Microscope
This type of microscope uses the polarizer by transmitting light vibrating in the vertical plane only. It’s similar to Polaroid sunglasses and it appears no different to the eye from ordinary light. The result makes the specimen readily distinguishable by allowing the polarized light to pass through the analyzer. It will then produce vivid colors and intensity in the contrasts, such as with soils and crystalline substances.
Microspectrophotometer
This microscope device is essentially combining and linking a new dimension of the computer to the microscope. It assists with visual comparison by enhancing color as with specimens such as paint, fiber, and ink evidence.
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Whether or not the crime is solved today, tomorrow, or sometime in the future, it’s important that every crime be taken seriously and all the appropriate steps are taken to ensure the integrity of the evidence, and hopefully the guilty will be brought to justice.
