If you respond to crime scenes you will inevitably come across black tire impressions on the concrete drive ways of the homes you respond to. I am sure that you can recall a time when you knew that one of those black tire impressions were made by the suspect vehicle. How will you capture the tire impression? Photographs will provide some detail, but in my experience, the detail is limited. I have found that there is more information there that is latent.
On a hot and humid Florida June day, I responded to a residential burglary investigation. The residence was a model home. The perpetrators had driven on and then off of the driveway and around the right side of the residence to position the suspect vehicle at the rear door of the residence. The perpetrators then took the kitchen appliances. Upon arrival at the crime scene, I noticed a dark tire impression on the driveway. The location and direction of the tire impression, made it clear that it was made by the suspect vehicle. See Figure 1.
After doing my initial photographs of the scene, I got my tripod and scale out of the van and took some photographs of the impression, but I really wanted to lift it. During a what if moment, I took out my electrostatic dust lifter and tried lifting a portion of the tire impression. I was surprised to find that the impression lifted with considerably more detail than I would have ever expected. In addition, there were footwear impressions on top of portions of the tire impression. These impressions were made by the complainant who was wearing Sperry boat shoes and his son who was bare foot. In addition, one of the footwear impressions was made by the responding deputy, who was quickly educated after I showed him his shoe print on top of the tire impression. See Figure 2.
Since then, I have used my electrostatic dust lifter every time I have seen a tire impression on a concrete driveway. Each time I have lifted a detailed impression. The interesting thing is that these driveways were not painted or treated with anything special. They were ordinary, porous, concrete driveways. Figure 3 shows a detailed electrostatic lift of a tire impression from a concrete driveway.
The light color and the texture of the driveway present problems with getting detailed photographs of these impressions. The electrostatic dust lift gives superior detail and clarity. Figures 4 and 5 show a comparison between a photograph and electrostatic dust lift respectively.
MATERIALS AND METHODS
Before lifting the impressions, it is important to document where the impression was lifted. Utilize standard tire documentation procedures. Once the impression is documented, I lift the impression. I prefer to utilize the rolls of the electrostatic dust film versus the sheets. The roll allows you to capture whatever length of the impression you would like, which is important with tire impressions when you consider the circumference of the tire. I utilize a standard ESDL that you can get from just about any forensic supplier.
The only difficulty I have experienced has been laying the film down on the impression when there has been wind. Tape and an extra hand from the responding deputy will help with laying the film down onto the impression. Tape one end down and unroll down the length of the impression until you reach the desired length. Cut the film and tape it down. If the tape doesn’t stick, you may have to find something weighted to hold it down.
I have also experimented with black gel lifters. I was able to lift some of the impression, but it was not as successful as the electrostatic dust lifter. I have also found the gel lifter inferior for several other reasons. The first reason being the gel lifter is limited in size in both width and length. To get a representative sample of the circumference of the tire, several gel lifters would need to be used, and the gel lifters tend to be expensive. Another reason is that the gel lifter has difficulty adhering to the surface of the concrete due to the dirt and debris on the driveway.
I can only speculate on how these dark tire impressions are made. It seems to me that the tire is heated up as it drives down the road and allows just enough tackiness to collect road debris (dust, dirt, rubber etc.). Then as the tire enters onto a driveway, the debris is laid back down. The darker the material collected, the darker the tire impression. I will speculate that there are more latent impressions present of lighter material. More research could be done on how the tire collects and deposits the debris and how often the latent impressions are missed.
In conclusion, the electrostatic dust lifter is a great tool for lifting dust footwear and tire impressions off of concrete. In addition to the ability of lifting tire impressions, it has made me aware that there may be latent footwear and tire impressions present on the driveways and sidewalks of the crime scenes I respond to.
ABOUT THE AUTHOR
Ron Mueller is a Crime Scene Technician with the Charlotte County Sheriff’s Office in Punta Gorda, Florida. He received his bachelors in science from Florida Gulf Coast University in Criminal Forensic Studies. He is also certified by the IAI in crime scene, footwear examination, and latent print examination. He has been doing Forensic work for 10 years.
The article has been submitted for publication in the JFI and the FDIAI newsletter, but has not yet been published.