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Monday, December 18, 2017 MAGAZINE Volume 1, Issue 1

The Case of the Obfuscated Tire Impression


by Michael F. LaForte

June 5, 2012

What do tire impressions and shoe impressions have in common? Some would say a lot of hard work, and others might say they require specific photographic techniques. Others try to avoid them at all cost. The reason this type of evidence is often ignored is because it is hard work, it can be very time consuming, and it does require very specific photographic skills. The fact is a tire or shoe impression is as good as a fingerprint.

I am sure that many of you have heard of tire and shoe impression evidence being referred to as "the forgotten evidence." With the technology crime scene units have available today, there really is no reason for overlooking, disregarding, or ignoring any type of impression evidence.

Tire and shoe impressions at an exterior crime scene, just like DNA evidence, require your attention much sooner than would be necessary at an interior crime scene. Because impressions at an exterior scene are subject to destruction from the sun, wind, rain, snow, and onlookers, not to mention other police, they must be dealt with in a timely manner.

Do not be the reason why a guilty person remains free because you failed to recover the only piece of physical evidence at the crime scene. On the flip-side, don't be the reason an innocent person is convicted on circumstantial evidence, because you failed to locate and recover the one impression that would have proved his innocence. I hope the following story illustrates just how important impression evidence at any crime scene can be.

Figure 1

Figure 1: The above view shows the parking lot from the victim's body to the road. Notice the tire impressions that are present in the dirt.

On July 5, 1990, at approximately 7:00 a.m., I was dispatched to a homicide scene located in a residential and commercial area of northwest Jacksonville, Florida. Passersby had discovered the body of a black male lying at the rear of a dirt parking lot on the south side of the street (Figure 1). The parking lot measured approximately 100 feet wide and 75 feet deep. The key word here is "dirt".

Upon my arrival, I found three patrol officers standing around the body with three patrol vehicles parked nearby. Yes, all three officers drove their vehicles across the dirt lot instead of parking on the asphalt road and walking in along the perimeter of the lot.

Note: Dirt, mud, and sand mean only one thing in police work: impression evidence! It is important for all first responders to understand and remember this.

In addition to the three police vehicles, there was also a fire engine and fire rescue unit parked next to the patrol units, yes on the dirt lot, and at least four fire personnel standing next to the three police officers. It was safe to assume a crime scene perimeter had not yet been established.

Since the surface at this scene was dirt, it was important to stop further destruction of the impression evidence that was most likely present and being ignored. The removal of the vehicles was orchestrated in such a way to reduce the further destruction of any impression evidence. Once all of the vehicles and personnel had been removed, the scene was secured with barricade tape and the search began for relevant physical evidence which included tires and shoe impressions.

The fully clothed victim was found lying on his back at the rear of the parking lot. There were residences that bordered the parking lot on the east, west and south sides. A large warehouse was located across the street, north of the victim. The location of the parking lot, bordered on three sides by trees reduced the chances of any eyewitnesses.

Figure 2

Figure 2: The position of the arms and legs suggests removal from a vehicle. The arrow above the victim's head points north.

A visual examination of the victim's body and the scene revealed the following:

  • The victim was found lying on his back.
  • The victim's arms were extended above the head.
  • The victim had a cast on his lower right leg.
  • The left leg was across the right leg.
  • A pair of tennis shoes were on the ground above the victim's head.
  • The bottoms of the victim's bare feet were not dirty. (He didn't walk to this location.)
  • The victim had a gunshot entrance wound behind the left ear.
  • There was no gunshot exit wound.
  • Bloodstain evidence on the body showed movement.
  • A small trickle of blood was observed coming from the entrance wound and down the left front of the victim's chest. This was consistent with the victim being in some kind of upright position when shot.
  • A small amount of blood was also observed running from the right nostril, downward across the right cheek. This was consistent with the present position.
  • Position of the body suggested the victim had been transported to this location in a vehicle and dumped. Either pulled out of a trunk or backseat (Figure 2).

Our crime scene unit policy required a minimum of two crime scene detectives work a homicide scene. As soon as we concluded the preliminary crime scene photographs, I began searching for relevant tire and shoe impression evidence while the other crime scene detective took care of processing the body.

Figure 3

Figure 3: The above examination quality photograph of the tire impression was identified as those from the suspect's vehicle.

A great deal of time was required to eliminate the numerous tire and shoe impressions that had been superimposed over the impressions presumed to have been deposited by the suspect vehicle. However, even though the crime scene had been contaminated by multiple first responders and their vehicles, this should never be a deterrent to not conducting a thorough search. Unless a search is conducted properly, it can never be determined that impressions, of any kind, do not exist.

What we believed to be probable suspect tire and shoe impressions were then diagrammed and photographed. Once the examination quality photography was completed, each impression was cast with dental stone (Denstone). Dental stone is far superior to Plaster of Paris, and if your agency is not using dental stone, I highly recommend you consider making a change. It took a total of about four hours to identify, photograph, cast, and collect the shoe and tire impressions.

Other than the body, this homicide case had no physical evidence. Remember, this was 1990, when DNA was still in its infancy. We were still three years away from receiving our first alternate light source. Even the collection of hairs and fibers was not yet a common practice at our agency.

Figure 4

Figure 4: After being photographed, the tire impressions were then cast with dental stone, allowed to air dry and were then collected.

The denstone casts and the examination quality photographs were submitted to the Florida Department of Law Enforcement (FDLE) crime lab in Jacksonville, Florida by the lead homicide detective (Figures 3 and 4). The analyst was able to identify the brand and size of the tires and the make of vehicles on which these tires could be found.

With this information, homicide detectives recalled interviewing an associate of the victim who drove one of the makes of vehicles identified by the crime lab analyst. Detectives went back to his residence and re-interviewed him. Detectives determined that this person had never let anyone else drive or borrow his vehicle prior to the homicide. A search warrant was then obtained for the vehicle which was then taken to the FDLE crime lab for processing. Crime lab personnel were unable to locate any physical evidence inside or outside of the vehicle connecting the victim to the vehicle. The tires on the vehicle were then inked and rolled for comparison.

Upon comparing the tires with my photographs and the dental stone casts, a positive match was made. This information placed this specific vehicle and no other at the scene of the crime. With this, detectives brought the subject in for an interview and when provided with this information, he confessed to the killing. He pled guilty to second-degree murder and was sentenced to the maximum possible.

This case is a perfect example of the importance of tire and shoe impression evidence. Over your career, there will be many scenes where a fingerprint cannot be found or does not exist. However, a tire or a shoe impression, with enough wear characteristics, can be identified to a specific individual to the exclusion of all others. That is powerful evidence!

Michael F. LaForte is a forensic consultant for Knox & Associates, LLC, a Jacksonville, Florida based forensic consulting company that specializes in firearms, ballistics, and crime scene reconstruction. He was a police officer/detective with the Jacksonville Sheriff’s Office for over 29 years having worked in patrol, and crime scene investigations. In addition to being a major case crime scene detective, he spent the last three years as the training coordinator for the agency’s crime scene unit. He has also provided crime scene training in Peru, and around the United States. He has testified as an expert witness in crime scene reconstruction in state courts in Florida. He has authored three books on crime scene processing and crime scene photography.