Written by Christopher D.
CRIME SCENE INVESTIGATORS MUST BE PREPARED to recover almost any
kind of object or process for any kind of evidence at crime scenes. Vehicles
are no different than a crime scene in the field, but they do have the benefit
of being processed in a more controlled environment. Investigators should take
advantage of this opportunity.
One type of vehicle that will frequently enter the facility will
be one from a hit-and-run investigation. Typically, accident or crash
investigation units handle hit-and-run investigations, also known as Fail to
Stop and Render Aid (FSRA) or Fail to Stop and Give Information (FSGI).
However, not every agency will have an investigator specifically assigned to
process vehicles involved in a hit-and-run investigation or the hit-and-run
incident was not an “accident,” but rather it was intentional, which changes
the agency’s investigative division’s responsibility. There are a couple of
common requests made when processing hit-and-run vehicles, and they revolve
around the need to identify what came into contact with the said car, whether
it was another car, object, or a human being.
When two vehicles impact each other, there is generally an
exchange of paint between the two vehicles. Edmund Locard’s “Theory of
Exchange,” which states “Every contact leaves a trace,” dictates that there
will be a transfer of material between the two contacting surfaces.
Recovering the paint or debris left behind is the job of the
evidence technician. Removing debris and paint from a vehicle is typically done
by scraping the material with a sterile surgical blade or a knife that has been
thoroughly wiped down with isopropyl alcohol. Paint transfers from minor
impacts may not come off as easily with just a surgical blade or scalpel.
However, this does not preclude the investigator from recovering such
evidence. More severe impacts likely will cause a vehicle’s paint to crack and
is much easier to scrape off.
Whichever tool is chosen to scrape the material or unknown paint
from the vehicle, the unknown paint or debris is scraped into an evidence
envelope or a druggist-fold envelope for collection. Paint chips have a
tendency to chip away at odd angles. Therefore, investigators should be
cognizant of that possibility and keep the scraping action or force downward,
so that all material is going to be pushed or fall into the evidence envelope
that is held just below the area being scraped. Eventually, the envelope will
be sealed and marked with the case information. If the unknown paint transfer
was scraped from the examined vehicle’s own painted surface, investigators
should also collect a known paint sample of the vehicle being examined and from
the same surface, but away from the damaged portion of the automobile. The
collected sample should be approximately the size of a United States quarter.
As far as the unknown paint or debris collected, it is recommended to collect
as much of the foreign material as possible. One does not need to stuff an
evidence envelope full of material, but no one is going to complain if “too
much” evidence is collected.
of hit-and-run accident that sadly is all too common are vehicle-pedestrian or
vehicle-bicycle hit-and-run crashes. If a suspect vehicle is brought into an
examination facility, it is up to the evidence technician to find traces of the
victim on the vehicle. Depending on where the impact was on the vehicle, it may
be necessary to have the vehicle lifted on the car lift and to look on the
vehicle’s undercarriage for trace fibers, DNA, or other pieces of evidence.
Fiber evidence can be collected and placed into a druggist fold or glassine
envelope. A suspect may wash the exterior of the vehicle but may forget to do
the unseen areas—so be sure to look for evidence underneath the vehicle, stuck in the radiator’s front cooling
fins, or behind the grill or other trim pieces (Figure 1). If the vehicle has
been cleaned by the suspect, what remains may be just a single fiber or two. If
the victim was run over, the undercarriage of a vehicle should be thoroughly
examined and special attention paid to any swipe marks visible through the
grime commonly found on the undersides of vehicles. Even if no physical
evidence is located underneath a vehicle, any swipe marks observed on the
vehicle should be photographed and fully documented. It may be circumstantial
evidence, but the evidence is evidence. Blood, tissue, and other serological
evidence can be collected through the swabbing technique detailed in Chapter 7.
task requested during crash investigations is determining the identity of the
driver or the positions of passengers at the time of a collision.
Investigations should search for and recover any bloodstains found inside the
vehicle. If bloodstains, hair, or tissue are not found, then the investigator
should collect touch-DNA swabbing samples from the vehicle controls, seatbelt
straps, and any deployed airbags. Airbags generally deploy with such force that
bloodstains or other body fluids are commonly found. The advantage of
recovering DNA from airbags is that it places a time stamp on when the individual
came into contact with the airbag.
course of vehicle crashes, pieces of a vehicle may be left behind at the scene
of a crime. Any vehicle glass, plastic, or other parts left behind at the crime
scene should be collected. The damaged pieces hold a great deal of information,
including the make and date of manufacture for a vehicle. Furthermore, if just
a portion of something is left behind at the scene, then it is possible to make
a fracture match between the two pieces. Consequently, when a suspect’s vehicle
arrives at a vehicle examination facility, which has damaged trim and/or glass,
these items should be examined closely. Vehicle examiners should remove damaged
parts of the vehicle so that any potential fracture matches can be made between
the debris left behind at the crime scene and the remaining pieces left on the
vehicle (Figure 2).
and window glass all have part numbers stamped or printed on them somewhere.
Therefore, even if the car was repaired, one may be able to compare part numbers
or date codes and determine if the vehicle had been repaired. For example, if a
taillight assembly was damaged at a scene, but repaired by the suspect prior to
the vehicle being seized, the examiner may be able to show that the vehicle’s
model year and the repaired part’s manufacturing year are different (Figure 3).
how vehicles are manufactured, parts are generally date coded within 30 days of
the vehicle’s assembly date. Some of the manufactured dates will not be as
clear as a numbered date but will be printed in a code. This is especially true
with car window glass. Date codes on windows can be a unique arrangement of
letters, numbers, and even through small dots placed next to letters on the
information printed on each window (Figure 4). There is no standard between
manufacturers as to the date coding of window glass or vehicle parts. Some of
this coded information may be deciphered through an internet search, but others
might require contacting the manufacturer for decoding of the information.
vehicles, whether accidental or intentional, present another unique type of
investigation that requires a whole new set of investigative skills. Arson
investigators are commonly cross-trained in fire and police investigations and
many times will take the lead during the examination of burned vehicles. They
will look at a burned vehicle and attempt to determine the cause and origin of
the fire. Fire science and the determination of the cause and origins of fire
are well beyond the scope of this book. However, there are a few tasks an evidence
technician can do to assist arson investigators. One is to positively identify
the vehicle through VIN plates remaining on the vehicle (Figure 5).
every investigation, the photographer should thoroughly document the vehicle
with photographs, especially in the area where the most fire damage occurred.
The origin of the fire is generally the location where the most fire damage is
found because the fire had more time to burn. The cause may be found by
locating the source of ignition or telltale signs of an accelerant being used
in the car. Many accidental fires will start in the engine compartment and
spread from there. If a fire started anywhere else, the arson investigator will
look carefully for any signs that an accelerant was used, such as a gas can or
a burn trail leading away from the vehicle at the recovery scene. The crime
scene investigator or evidence technician should follow along with the arson
investigator and photograph all key aspects of the investigation.
of severely burned vehicles will have to be sifted through very carefully to
look for evidence and even for deceased bodies. One must be cognizant of what
fire can do to objects and to human bodies. Fire will burn off much evidence,
but others will take on different forms. For example, plastic gas cans may melt
and be found as charred-red disks of plastic instead of their original
container shape. Bodies can be burned away similarly and extremely hot fires
can turn a body into hundreds of calcined bone fragments that are extremely
delicate and must be recovered with extreme care. Having a forensic
anthropologist would be extremely helpful when a burned body is located. They
can be enormously helpful in recognizing osseous matter and may even be able to
identify bone trauma that might give an indication as to the fire victim’s
cause of death. Investigating crimes and especially crimes involving fire is
definitely a team effort and any help offered to an evidence technician should
through a burned vehicle is done by sifting through layers of debris found in
the car. This can be done by using a small brush and a dustpan and by removing
debris from the vehicle a little at a time. In this way, one will be less
likely to miss a small piece of evidence, like a melted, fired bullet. Do not
forget to photograph as the search progresses through the various layers of
debris (Figure 6).
evidence, taking special note of exactly where each item was found. The arson
investigator will likely take care, custody, and control of any arson evidence,
while the forensic anthropologist will take responsibility for any human
remains. Everything else of value will be the responsibility of the evidence
Christopher (Chris) D.
Duncan graduated from
George Mason University with a BA in History and earned his MA in Criminology
from the University of Houston-Clear Lake. He is a retired senior police officer
with the Houston Police Department and was previously an active member of the
International Association for Identification. Duncan has written several
articles on forensic evidence collection and documentation and has more than 1,500
hours of training specific to the documentation, collection, and the processing
of physical evidence, having worked 20 of his 29 years in law enforcement
as a crime scene investigator. Prior to his days in the crime scene unit, he
was assigned as a patrol officer and a gang task force officer. Duncan now
teaches Criminal Investigation and Law Enforcement classes at Klein Collins
High School in Texas.