Editor’s note: The tools and practices discussed here are intended to help officers recognize, document and preserve potential evidence when appropriate. They are not a substitute for crime scene personnel, agency-approved training or legal guidance. Officers should follow their agency’s policies and procedures for scene security, searches, evidence collection, documentation and specialized callouts.
Half of good police work is finding the evidence before it disappears. The other half is proving you were the one who actually found it. In a lot of agencies, both halves fall on patrol because the crime scene tech is one person covering an entire county, is not working that day, or is stuck processing a homicide two counties over. Sometimes the tech simply isn’t coming, and the evidence does not wait for a callback. It gets rained on, driven over, kicked into the weeds, or walked off while you stand around waiting for someone else. A patrol-ready kit can help trained officers identify and preserve potential evidence while awaiting a technician or detective response.
This is not about replacing your crime scene unit. It is about working the cases with more efficiency, but within the scope of your policy. I love my crime scene technicians, and I am blessed to have a full team willing and waiting to help. Crime scene technicians bring training, certification, documented methodology and courtroom credibility. On a violent crime, a sexual assault, or any scene where the stakes and the scrutiny are high, the answer is still the same: secure it, hold it and get a tech. A defense attorney will take apart an officer who freelanced past their training, and they should.
But I found dozens of products you can use to build your own CSI patrol kit that still fall within most policies and evidence-handling requirements. Here are my top choices to start with.
Metal detector for finding evidence faster
If I could choose one tool that every patrol team should have, it would be the Garrett Vortex CSI Metal Detector. This is not a hobby metal detector, even though you can absolutely use it as one if you buy it yourself. Garrett’s CSI line is tuned specifically for weapons, bullets and shell casings.
The FBI’s own Law Enforcement Bulletin walks through exactly how an investigator should use a metal detector and the benefits of fast evidence recovery. That casing you find right now matters because, once you recover it, the lab can do its job of identifying prints and matching the firing-pin and breech-face marks to a specific weapon.
Honestly, I didn’t think I would use a metal detector in the field as much as I do. I have used it to search a weed-choked alley for a gun a suspect ditched while fleeing on foot; I have used it to grid the street and gutters after a drive-by shooting, looking for casings; and to search for a gun that was tossed in a dirty irrigation canal. The Garrett Vortex is waterproof up to 16 feet, which is why I like this version over all the others.
UV lights for seeing the invisible
“Don’t check your hotel room with a UV light” is probably good advice because with the right light you can see more than you probably want to. Ultraviolet and blue light reveal what the naked eye misses. Semen, saliva and urine are naturally fluorescent and glow at the right wavelength. You can quickly scan a mattress, a wall, or a car interior and pinpoint stains instead of guessing. If you find the right wavelength of light, you can even see dry sweat and sometimes fingerprints.
The uvBeast V3 385-395nm and 365nm are the most common wavelengths professionals reach for in forensic work because they produce high-contrast fluorescence. But my favorite use for these lights has nothing to do with body fluids. I like to use them to find dust, or lack of dust on dry surfaces.
I had a domestic where the victim said she had been shoved and pinned against a wall because her boyfriend was not letting her go. But she had no visible injuries, and we had no independent witnesses, which is a maddeningly common problem. No marks, no photos, and this was a he-said-she-said case that would go nowhere.
I used my uvBeast V3 on the wall exactly where she told me she was, and it lit up the disturbance. The smear of dust on the wall and the transfer pattern where someone’s hands, arms, and body had pressed and dragged across the surface were consistent with her account.
Just a couple of notes with UV lights. UV lights can’t determine what type of stain or where the stain came from. They just show what is there. If you need details, you may need to call your Crime Scene Technician to help you identify it.UV lights can also destroy DNA. Ultraviolet radiation damages DNA by fusing adjacent bases into thymine dimers that kink and break the strand. If you need DNA as evidence, don’t hold the light on the stain or stay away from UV lights altogether.
Blood light for tracking
Blood does not glow blue under a black light as it does on television. That is a myth. Of all the common body fluids, blood is the one that does not fluoresce. It absorbs light. Under an alternate light source, it goes dark rather than bright. That is why your UV flashlight, which is perfect for semen and saliva, is not for your blood investigations.
But a dedicated NEBO IllumaTrace blood tracking light will work just fine. The NEBO IllumaTrace uses specific wavelengths to make blood stand out against dark, cluttered, blended-in backgrounds. This light makes blood stand out against gravel, dirt, dark carpet and piles of clothes. Hunters have used these for years to follow a blood trail through the brush at night, and the crime-scene application is the same. You are looking for blood.
Imagine trying to track down a suspect or a victim in the middle of the night. All you have is a faint blood trail that seems to disappear. If you had the NEBO IllumaTrace, your job could be a lot easier.
Thermal imaging as a search aid
I originally started testing the TOPDON TC004 Mini to see whether it could help locate people hiding in tight spaces, such as attics or crawl spaces. While this compact, standalone thermal camera is not ideal for that purpose — particularly in hot southern climates — it can be useful for searching thick brush or determining whether a vehicle hood is still warm.
One legal line to respect. Thermal imaging is a lead generator, not proof of a fact by itself. The Supreme Court drew a bright-line rule in Kyllo v. United States against using thermal imaging to see inside a home without a warrant. Keep your use to lawful, plain-view, exterior searches to find people in places they are not legally allowed to be in the first place. Use it to point you to where to look, then develop the evidence in ways that will hold up.
Counter-surveillance for first responders
I have been to dozens of calls over the last few years of people claiming they have hidden cameras in their houses, or trackers on their cars.
As a patrol officer, it is nice to have a simple tool like the Kadncst hidden camera detector to help sweep a location for signals that can help you find hidden cameras and covert recording devices before calling out detectives in the middle of the night. There are lots of these devices on the market, from the cheap Kadncst one I purchased to professional-grade ones that cost thousands.
A cheaper scanner like the Kadncst is my go-to tool for the voyeurism complaints where victims are being recorded or think they are being recorded, and in domestic cases where a victim believes their abuser has them under surveillance. Once you confirm the presence of a device, stop and call your agency’s detectives for guidance. Use this tool as a pre-screening device to determine whether a detective call-out is warranted.
Where I put all of this
I have a lot of different tools that I test and use out in the field. Finding a place to store all this stuff can get tricky. I am in the process of building my own fancy case that can fit all my CSI equipment in its custom spaces, so I will do an update when I get to that point. But you don’t need anything fancy. You just need something to move the tools from your office to your car. My entire kit rides in an old soft rifle case with several rifle magazine pouches that hold my flashlights and scanners. Do not let the search for the perfect case stop you from carrying the kit you have. A repurposed rifle case, a hard-sided toolbox, even a solid range bag will get you started. Upgrade when you can and carry it in the meantime.
Before you start purchasing random CSI equipment, get to know each tool, its limits and the line where a finding needs a real evidence technician. Ask your technicians. They are there to help. Also, just because you have fun tools does not give you permission to expand your legal authority to search. Know your limits and hand off the major scenes.
The evidence does not wait, and “the tech could not come” is not an answer most juries accept. A patrol-level kit does not make you an independent crime scene unit and is not supposed to. It makes sure the cases your techs will never reach still get worked, and the scenes they do reach arrive better preserved than they are used to. Buy the training first. Then buy the gear.
