Some of your most important prep work for a crime scene should occur before you ever leave your office. First, remember to keep your crime scene vehicle fully stocked with the equipment and supplies that you’re likely to need no matter the type of crime scene. The more things you can carry to the scene, the better. After all, how likely is it that you’ll go back to the office to get additional supplies or equipment once you’re in the middle of processing the scene? Even if you could go back to your office, your time would be better spent processing evidence as soon as possible. Keeping your vehicle in good shape and properly stocked with supplies helps you do your job more accurately and more efficiently.

Also remember that working a crime scene should be a team effort for you and your department. One of the best things you can do is train the field officers and the first responders about your capabilities. These officers are your eyes in the field; it’s their job to call you when they see something that you can process. But if they don’t understand what you can do, they can overlook evidence, and you’ll never get that call.When I was on the force in Kansas, I made a point of teaching our patrolmen basic crime scene techniques like how to look for dust footprints and signs of DNA evidence, and it made a huge difference. Officers knew what to look for, and they called me to collect evidence that later proved to be invaluable to our cases.

As part of your initial assessment of any scene, gather as much information as possible about the complexity of the case so that you can determine whether you have enough people and the proper equipment to process the scene. Begin by doing a walk-through, making observations about how the crime was committed and the types of evidence you are likely to find. Once you complete the walk-though, you’ll know what you’re dealing with.

In cases such as a simple residential burglary, you may only need your standard equipment and regular staff. But a complex case or a major crime such as a homicide usually requires much more intensive processing. That means more equipment and more people working the case and, in some situations, additional specialists. The key is to be aware of your limits. You don’t want to mess up a case because you were too proud to ask for help; you’ll pay the price on the witness stand.

After the initial assessment, photograph the scene—leaving everything exactly the way it was when you arrived. As you photograph the scene, determine which items will need individual processing, but don’t move or touch anything. Look for signs of objects that seem to be out of place or that a suspect would be likely to come into contact with; these items should be fingerprinted later. Also look for small things like hairs and fibers. The average person sheds 150 hairs per day, so there’s a good chance you’ll find hair at the scene that belongs to the suspect. Be systematic in your approach so that you don’t miss anything. The smallest items can be very important to your case.

Once you have identified the individual items for processing, photograph each item using a scale before you do anything else. Process any item that can be handled at the scene for fingerprints and DNA evidence. These may include large items such as vehicles and countertops, and points of entry, such as window and door frames. For homicides or other major crimes, you may decide to take the entire window or door from the scene so that you can use it in court. Also check for dust footprints, fingerprints, blood, semen, and other DNA evidence. If you’re using luminol or BLUESTAR to look for possible blood at the scene, either wait until evening or block any light from coming through the windows.

Some items may require superglue fuming, ninhydrin, DFO, or other specialized processing. Carefully collect these items, and then place them in an appropriate package to be sent to the lab. Label each package with the proper case number, and keep a clear record of what you’re doing. A key point to remember is to keep the chain of custody as short as possible. The fewer people who handle the evidence, the fewer people who have to go to court to testify.

Working a crime scene requires a well-thought out process and attention to every detail. The “CSI Effect” is still present; the jury expects to see a full range of evidence. If you plan ahead and use your common sense, you’ll improve the odds that you’ll end up with a case that stands up in court and gets the results you want.

Dick Warrington is in research and development and a crime scene consultant and training instructor for the Lynn Peavey Company.