No matter the type of scene, you must carefully mark and record every piece of evidence you find. This may seem pretty straightforward, but it becomes more complicated when you have multiple crime scenes or incidents. By developing a system for marking evidence before you arrive at your crime scenes, you will avoid confusion and build stronger cases.

There are many possible systems that you can use to mark evidence. Your system must be clear to anyone working on the case, including other crime scene officers, lab technicians, and other experts. The clarity of your system is especially important when you go to court. You don’t want to get confused because of the way you marked your evidence. You need your evidence to be so clear and easy to understand that you can go back to your notes and follow what you did whether your case just happened in the last few months or 10–15 years ago. If your system of marking evidence is confusing, you could confuse everyone else, too. If the jury gets lost in the shuffle and misses the points you are trying to make, your case could fall apart.

Whatever system you decide to use, you need to make sure that it will work if you are dealing with multiple crime scenes, locations, or incidents. Homicides, in general, often include an initial crime scene but then expand to include multiple scenes at different times and different locations. There may even be different officers working each scene. How do you keep the evidence straight? You can’t simply start at the first scene, assign a case number, number the first piece of evidence as “1,” and then have other officers at the other scenes also labeling the first piece of evidence they find as “1.” If you do it this way, you end up with a number of evidence sheets, each with item number 1 and no way to distinguish them. Somehow you need to develop a system that will differentiate the scenes and the incidents so that you and everyone else who deals with the evidence will be able to tell exactly where each piece of evidence was found.

Taking the time to develop a clear system that is easy to use will be well worth the effort. Once you find a system that is easy to understand and follow, and that allows you to coordinate your evidence across your crime scenes, be sure to use it consistently. Nowadays, the courts are quick to jump on any mistakes in a case. Before you know it, the evidence is out, and your case is in serious trouble. If you can eliminate mistakes by being conscientious in handling your evidence, you’ll be in very good shape.

From: Marking Evidence at Crime Scenes: Developing a System by Dick Warrington