Collecting evidence is far more involved than what is shown on the screen. Any time evidence is collected from a crime scene, each piece must go through what is known as chain of custody. The term refers to the process of maintaining and documenting the handling of evidence. It involves keeping a detailed log showing who collected, handled, transferred, or analyzed evidence during an investigation(1). If a crime scene investigation is in your work, scoot up to the bar here. Also, check out my book Fight Write: Craft Chaos, Combat and Crime where I go into all this and more.
Collecting Evidence: Secure the Scene
Before any evidence is collected, you have to secure the scene first. Maybe it’s just me but I didn’t know what all that entailed! It’s more than just putting up tape.
First, treating the injured is most important. You don’t secure a scene while someone in it is bleeding out.
- Identify the focus of the crime be it an area or victims. Then you establish a perimeter around that focal point. It’s a good idea to make the perimeter bigger than the scene itself.
- Secure the area. Put up crime tape and place security at the tape.
- Create a command center or meeting point that is not a part of the scene.
- Determine the crime that occurred and then work to protect evidence. Identify what could compromise the evidence such as weather or pets. Make a plan with the team on how to proceed.
- Survey the area for evidence. Once you identify potential physical evidence, the chain of custody begins.
Tools and Dress for Collection
While collecting evidence, gloves are worn and single-use, disposable instruments are used. Those collecting evidence are careful not to touch areas where there could be DNA evidence. They also AVOID talking, coughing, sneezing etc.
Collecting Evidence: Chain of Custody Breakdown
- Photographs – Photographing generally goes from broad to minute. For example, photograph the scene as a whole, different areas, different areas within those areas and so on. Photograph victim as whole and then areas of visible injury. If the victim is alive and needs care, that takes precedent. Photos of their injuries can come later. Photograph evidence before the marker is placed and again after the marker is placed.
- Create detailed notes of each piece of evidence. Be sure to note:
- location of evidence
- time and date of recovery
- description of item
- condition of item
- unique markings
- Collect evidence and place all biological evidence in paper bags NOT plastic. Plastic holds moisture and moisture as well as sunlight in damaging to biological evidence. Yes, I know that you often see evidence placed in clear bags on TV and movies. That is for the sake of the audience. It is not correct procedure unless the evidence is non-biological such as pills, guns (not bloody), spent ammo etc. Wet evidence should dry before being placed in the paper bag. It can be placed in the paper while still wet if you need to hurry to preserve the evidence. For example, if the scene is outside and it’s about to rain, you can place wet evidence in the paper bag. That paper bag can be temporarily put into a plastic bag if the paper bag is dripping. You might read that wet evidence goes in paper and dry in plastic. That’s not correct. I consulted a forensic investigator on the subject. Also, if the biological evidence is old, such as bones, it can be vacuum sealed in plastic on-site and then transported to a freezer. Anyone who touches the evidence must be logged in the chain of custody.
Chain of Custody Forms:
Chain of Custody Bags, Paper and Plastic (You can buy these on Amazon btw.)
And here is a video that kind of walks you through the whole process. I hope this post was useful for you CSI writer types. If you have any questions any time, reach out through the contact form on the home page. Seriously. I love that stuff. Until the next round at FightWrite®, get blood on your pages!
