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In a recent article I discussed ways Crime Scene Officers can prevent crime scene contamination. As I noted, protecting the scene and evidence is crucial since contamination of evidence can jeopardize an entire case. But do you ever stop to think about how you might be contaminating your equipment? If you don’t consider this possibility and take steps to protect your equipment and decontaminate it when necessary, you could be putting yourself, your fellow officers, and the success of your case at risk. With some advanced planning and a little common sense, you can avoid many serious problems.
Contamination of equipment at a crime scene is a serious problem and can occur in many ways. Any time your equipment comes into contact with blood, fluids, or other substances at a scene, you run the risk of contamination. For instance, if you touch a body and then grab your camera, you’ve contaminated your camera. If you set up a tripod on the ground, it may be in blood or some other fluid. If you’re outdoors, soil may stick to the tripod. If you’re not paying attention and don’t decontaminate your equipment, you can transfer evidence to other parts of the scene or to a new scene. You can’t afford to make these kinds of mistakes.
Take steps ahead of time to control contamination at the scene. You can avoid many problems if you arrive with the proper equipment and a clear plan for protecting yourself and your equipment. Obviously, some scenes will present more risks than others. At a homicide scene, for example, there may be blood and other fluids from the victim and/or the suspect everywhere, so you’ll need to be especially vigilant. A scene with a decomposing body is probably the worst type of scene. In addition, if you attend an autopsy, assume that the whole room is contaminated and take appropriate precautions. For most cases, it may be weeks before lab results are back, so it’s best to err on the side of caution.
When you arrive at the scene, establish secure, central areas for clean equipment, items to be disposed of, and items to be decontaminated. For the first area, I used to take a clean biohazard bag, open it up, and spread it on the ground. I then put all of my clean equipment, including things like fresh gloves and booties, on top of the bag. That way, I knew anything on the bag was still clean. Once I used an item, it went somewhere else. For items that need to be disposed of, set up a separate area with clean, unopened biohazard bags. Remember to bag these items, but don’t throw them away until you know you won’t need them for your case. Then set up a third area for non-disposable items that may be contaminated. These items should be cleaned before you pack up. Use either a mixture of bleach and water or Clorox disinfectant wipes to decontaminate them.
While processing the scene, think about ways to limit your exposure and keep the scene clean and safe. Wear appropriate protection, such as Tyvek suits, gloves, booties, and masks, especially when dealing with bodies. Dispose of suits after use; don’t try to reuse them. Change gloves often. Any time you touch a body or other item, get a new pair of gloves. At some scenes, you may go through 25–30 pairs of gloves. Your superiors may question you about this—I know mine did. But when I explained that I was doing it to prevent cross-contamination, they understood. Spending a little more on gloves is worth it to protect the integrity of the scene and to protect the health of officers. Make sure everyone follows the same procedures and has the correct equipment. I used to set up meetings with officers and first responders from the local fire station to explain our contamination control procedures. Making the effort to educate others helps get everyone on the same page.
Also look for ways to protect your equipment. For example, you can make “booties” for your tripod from rubber gloves. Cut off the fingers and pull the gloves over the legs. Put on a fresh pair of gloves before you pick up your camera. Even with these precautions, decontaminate any non-disposable items that may be contaminated. Also be careful with anything used for measurement. It’s easy to pick up a ruler, place it on a body, and then put it down on another surface. But once the ruler touches the body, it’s contaminated, and so is the new surface. You can avoid this problem by cleaning rulers and other devices every time you use them. You can also use disposable items. You should also dispose of brushes and fingerprint powders after use. These items will become contaminated with evidence from your scene; you don’t want to carry that evidence to the next one. Make sure you bag and label any disposable items after use in case the attorneys want them for court.
A crime scene is often a chaotic place. It can be all too easy to make careless mistakes. If your equipment becomes contaminated, it may cost you the case you’re working on and put future cases at risk. You may also be endangering yourself and others. Guard against these problems by establishing guidelines for dealing with contamination and making sure everyone follows the rules. A little common sense goes a long way.
Dick Warrington is in research and development and a crime scene consultant and training instructor for the Lynn Peavey Company. firstname.lastname@example.org