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					                                            Trace Evidence
                                           By Katherine Ramsland
                                           CourtTV Crime Library
Introduction
In 1936 the wife of an NBC executive was killed in their Manhattan brownstone. She had been
strangled with her pajama top and left in the bathroom. All indications were that she had known
her killer, and when there appeared to be few clues except some twine used to bind her, a
chemist was brought in to examine the crime scene.

In the bedroom he found only one strand, half an inch long, of stiff white hair, which he soon
identified through a microscope as horsehair. Since two furniture movers had delivered a
horsehair couch that morning and it was those men who reported the body, the detective in
charge speculated that one of them had paid an earlier call. He identified the likely culprit and
then found a connection via the piece of twine, because it had sufficiently distinctive markings to
be traced to a manufacturer and distributor. It turned out that the same twine had been sold to the
furniture store. Using this evidence to put pressure on the suspect, the detective got the
confession he needed for conviction. This was one of the early cases where technology was used
on material fragments to solve a murder.

Every person who is physically involved in a crime leaves some minute trace of his or her
presence, and often takes something away. This is Dr. Edmond Locard‟s principle of contact,
proposed when he began his forensic laboratory in 1910. He closed a case two years later by
examining what was under the fingernails of a female victim, and thereby showed how
seemingly insignificant matter can make all the difference.

No matter how much someone tries to clean up a crime scene, something is generally left behind.
It may not always be detected, but it‟s difficult to take any kind of violent action without
shedding something. This principle became the motivating factor in the development of forensic
science.
                    An attorney displays fiber and hair evidence samples in court (AP)


Trace evidence, though often insufficient on its own to make a
case, may corroborate other evidence or even prompt a
confession. Because trace evidence can be any number of
things, from a paint chip to a piece of glass to plant debris, there
are numerous different methods used for analysis. For some
objects, there is a large database available for comparisons,
while the science of others has not advanced that far. The main
point is that some apparently foreign object or piece of material
is present at a crime scene and tracing its origin can assist in an arrest and conviction. Similarly,
finding some trace from the victim or crime scene on a suspect can have a strong impact on a
case.

While there is no end to the types of trace evidence that can be found, most investigations center
on fiber or hair, which is easier to see than pollen or dirt. Cases involving those substances will




Trace Evidence                                                                                 page 1
be covered at length, but some of the more unique types of trace evidence that have helped to
close cases are included as well.

Let‟s look first at a controversial case involving fiber.

                              Fibers and Probability Theory
From 1979 to 1981, someone was killing Atlanta‟s youth. More than twenty-five black males,
some as young as nine, had been strangled, bludgeoned or asphyxiated. A few females were
killed and some children were just missing, but all potential leads turned into dead ends. The
only real clue – which was valuable only if a suspect surfaced – was the presence on several of
the bodies and their clothing of some kind of fiber threads. A few also bore strands of what wa s
determined to be hair from a dog.

These specimens were all sent to the Georgia State Crime
Laboratory for analysis, and technicians there isolated two
distinct types: a violet-colored acetate fiber and a coarse yellow-
green nylon fiber with the type of tri-lobed (three branch)
qualities associated with carpets. They searched unsuccessfully
for the manufacturer.

The fiber discovery was reported in the newspaper and shortly
thereafter, bodies were found stripped and thrown into the river. Some authorities surmised that
the killer believed that the water would wash away trace evidence. They took it to mean that the
killer (or killers) was paying attention to the media. (Others, however, did not think that all of
these deaths were related.)

                                   Wayne Williams (AP)


                                 Since the unknown predator seemed to favor the Chattahoochee
                                 River, the police set up a stakeout. On May 22, 1981, this
                                 strategy appeared to pay off. In the early morning hours, the
                                 stakeout patrol heard a loud splash. Someone had just thrown
                                 something rather large into the river. On the James Jackson
                                 Parkway Bridge, they saw a white Chevrolet station wagon, and
                                 when they stopped it, they learned that the driver‟s name was
                                 Wayne Williams. He was a 23 year-old black photographer and
                                 music promoter. They questioned him, but when he said he‟d
just dumped some garbage they let him go. (Later he would claim that he‟d come there to see
the stakeout, having heard about it from friends in the police force.)

Only two days later, the police found what they believed had been the source of the splash – the
body of 27-year-old Nathaniel Cater. He was dredged up about a mile from the bridge, and
despite his murderer‟s carefulness, a single yellow-green carpet fiber was found in his hair. (The
assumption was that it had stuck there despite the water rather than thinking that he might have
acquired it in the water.) Cater also showed signs of asphyxiation, but it was difficult to



Trace Evidence                                                                              page 2
determine just how this had happened. Nevertheless, the medical examiner thought that he had
been dead for at least two days.

The police got a search warrant for Wayne Williams‟ home and car, and the search turned up a
valuable piece of evidence: The floors of Williams‟ home were covered with yellow-green
carpeting, and he also had a dog. Comparisons from the samples removed from the victims
showed good consistency with Williams‟ carpet. Although Williams claimed to have an alibi,
the description he gave of his movements the night they found him on the bridge was partly false
and partly unsubstantiated. Three separate polygraph tests indicated deception on Williams‟
part.

Then FBI experts analyzed samples from his rugs. With special equipment, and in consultation
with DuPont, they managed to ascertain that the fibers came from a Boston-based textile
company. The fiber was called Wellman 181B and it had been sold to numerous carpet
companies. Each uses its own dye, so that made it possible to narrow down the likely source,
which was the West Point Pepperell Corporation in Georgia. Their “Luxaire English Olive”
color matched that found in Wayne William‟s home. There were also similarities between the
hair from Williams‟ dog and the dog hair found on several victims.

However, many other homes had this carpeting installed, too. Thus, it had to be determined just
how likely it was that Williams‟ carpeting was unique enough to persuade a jury of his
connection to the murders. The next step was calculating the odds.

A look into company records turned up information that they had only made that type of carpet
during a one-year span of time, with over 16,000 yards of carpet distributed throughout the
South. In comparison with the total amount of carpet distributed across the country, this was a
very small sample. That made the statistical probability of the carpet being in any one person‟s
home to be slight, if it could be assumed that Luxaire English Olive had been fairly evenly
distributed. Altogether they figured that around eighty-two homes in Georgia were carpeted with
Luxaire English Olive. That meant the odds were stacked against finding many homes in
Atlanta: 1 in 7792.

To make their case, the prosecution relied on only two of the twenty-eight suspected murders---
the one from the river, Nathaniel Cater, and another recovered in the same general area a month
before, Jimmy Ray Payne (although it had not been concluded that he had been murdered). A
single rayon fiber had been found on his shorts, which was consistent with the carpeting in
Williams‟ station wagon. In this second case, statistical probability was also employed. With
Chevrolet‟s help, the investigators determined that there was a 1 in 3,828 chance that Payne had
acquired the fiber via random contact with a car that had this carpeting installed.

When the odds in both cases were multiplied, the law of probability that both men could have
picked up these fibers in places other than Williams‟ home and car came out to 1 in almost
30,000,000. That seemed pretty staggering.

The prosecution also introduced into evidence the fibers found on the bodies of ten of the other
victims (allowed in Georgia courts), which also matched those in Williams‟ car or home. These,



Trace Evidence                                                                             page 3
they claimed, showed a pattern, and taken altogether, it increased the odds in the fiber evidence
into numbers that no one could even comprehend. In total, there were 28 fiber types linked to
Williams. In addition, several witnesses had come forward to place Williams with some of the
victims, and others claimed to have seen suspicious scratches on Williams‟ arms.

After only twelve hours, the jury returned a guilty verdict, with two life sentences. The police
announced that twenty-two of the unsolved murder cases were now closed, despite the fact that
there was no real proof for those victims.

Subsequently the Williams conviction has become controversial. To understand this, let‟s look
at how fiber analysis is done.

                                        Fiber Analysis
Cross transfers of fiber often occur in cases in which there is person-to-person contact, and
investigators hope that fiber traceable back to the offender can be found at the crime scene, as
well as vice versa. Success in solving the crime often hinges on the ability to narrow the sources
for the type of fiber found, as the prosecution did with their probability theory on the fibers in the
Williams case.

The problem with fiber evidence is that fibers are not unique. Unlike fingerprints or DNA, they
cannot pinpoint an offender in any definitive manner. There must be other factors involved, such
as evidence that the fibers can corroborate or something unique to the fibers that set them apart.
For example, when fibers appeared to link two Ohio murders in the 1980s, it was just the start of
building a case, but without the fibers, there would have been no link in the first place.

In 1982, Kristen Lea Harrison was abducted from a ball field in Ohio and her body was found six
days later some thirty miles away. She had been raped and strangled. Orange fibers in her hair
looked suspiciously like those that had been found on a twelve-year-old female murder victim
from eight months earlier in the same county. Since they were made of polyester and were oddly
shaped (trilobal), forensic scientists surmised that it was carpet fiber. In addition, a box found
near Kristin‟s body and plastic wrap around her feet indicated that the killer had once ordered a
special kind of van seat, but then leads dried up.

Some time later, a 28 year-old woman was abducted and held prisoner in a man‟s home. He
tortured her and appeared to be intent on killing her. When he left, she escaped and reported
him. Police noticed that he had a van similar to the one into which Kristin had been forced. It
proved to have orange carpeting that matched the fibers in her hair. The color was unique, which
allowed scientists to trace it to a manufacturer who supplied information about its limited run.
Apparently only 74 yards of it had been shipped to that area of Ohio. That helped to narrow
down possibilities. Other evidence established a more solid link and Robert Anthony Buell was
eventually convicted.

Fibers are gathered at a crime scene with tweezers, tape, or a vacuum. They generally come
from clothing, drapery, wigs, carpeting, furniture, and blankets. For analysis, they are first
determined to be natural, manufactured, or a mix of both.



Trace Evidence                                                                                 page 4
Natural fibers come from plants (cotton) or animals (wool). Manufactured fibers are synthetics
like rayon, acetate, and polyester, which are made from long chains of molecules called
polymers. To determine the shape and color of fibers from any of these fabrics, a microscopic
examination is made.

Generally, the analyst gets only a limited number of fibers to work with – sometimes only one.
Whatever has been gathered from the crime scene is then compared against fibers from a suspect
source, such as a car or home, and the fibers are laid side by side for visual inspection through a
microscope.

A compound microscope uses light reflected from the surface of a fiber and magnified through a
series of lenses, while the comparison microscope (two compound microscopes joined by an
optical bridge) is used for more precise identification. A different device, the phase-contrast
microscope, reveals some of the structure of a fiber, while the various electron microscopes
either pass beams through samples to provide a highly magnified image, or reflect electrons off
the sample‟s surface. A scanning electron microscope converts the emitted electrons into a
photographic image for display. This affords high resolution and depth of focus.

Another useful instrument is the spectrometer, which separates light into component
wavelengths. In 1859, two German scientists discovered that the spectrum of every organic
element has a uniqueness to its constituent parts. By passing light through something to produce
a spectrum, the analyst can read the resulting lines, called “absorption lines.” That is, the
specific wavelengths that are selectively absorbed into the substance are characteristic of its
component molecules. Then a spectrophotometer measures the light intensities, which yields a
way to identify different types of substances.

A combination of these instruments for the most effective forensic analysis is the micro-
spectrophotometer. The microscope locates minute traces or shows how light interacts with the
material under analysis. Linking this to a computerized spectrophotometer increases the
accuracy. The scientist can get both a magnified visual and an infrared pattern at the same time,
which increases the number of identifying characteristics of any given material.

The first step in fiber analysis is to compare color and diameter. If there is agreement, then the
analysis can go into another phase. Dyes can also be further analyzed with chromatography,
which uses solvents to separate the dye‟s chemical constituents. Under a microscope, the analyst
looks for lengthwise striations or pits on a fiber‟s surface, or unusual shapes – as with the one
short and two long arms of the trilobal fibers in the Williams case.

In short, the fiber analyst compares shape, dye content, size, chemical composition, and
microscopic appearances, yet all of this is still about “class evidence.” Even if fibers from two
separate places can be matched via comparison, that does not mean they derive from the same
source, and there is no fiber database that provides a probability of origin.

Since the Wayne Williams case pretty much came down to fiber evidence, it‟s obviously open to
serious challenge. Chet Dettlinger is a former assistant to the Atlanta Chief of Police. He and a
group of other high-ranking ex-law-enforcement officers independently investigated the case.



Trace Evidence                                                                               page 5
Dettlinger, now a Georgia attorney, was asked by Williams‟ defense lawyer, Al Binder, to act as
a consultant, and he co-authored, The List, the only book to be published on the case. Among
other problems, he saw glaring errors with the way the fiber evidence was presented.

“The „matching‟ fibers were taken only from victims,” he says.” Only one individual red cotton
fiber was found at the Williams home, which can be found in abundance at K-Mart or Walmart,
which is similar to fibers in victim Michael McIntosh‟s underwear. That came from the vacuum
sweepings of a car, which the Williamses may or may not have owned at the time that McIntosh
was murdered. Not one fiber from any victim was found anywhere near the carpet in the
Williams‟ house.

“Insofar as the Wellman fiber is concerned, they were attempting to demonstrate how rare the
fiber in the carpet in „Wayne Williams‟ room‟ was. This ignores the fact that all of the
Williamses, and any regular visitor to the home, existed in the same environment.”

Dettlinger goes on to pinpoint the central errors in the prosecution‟s probability analysis as:

1. They ignored the fact that the same carpet was in all but one or two rooms in the house,
   including the parents‟ bedroom and the living room.
2. They overlooked the fact that Wayne Williams had changed rooms since the last murder on
   their list. The room they identified as his was actually used by a relative.
3. They ignored the fact that even in residential applications many of the exact same fibers were
   dyed the same color and used in rugs which are not the same model number as those used in
   the Williams‟ house.
4. They chose to narrow their analysis to a statistical area that doesn‟t exist – the southeast.
   They also failed to allow for the possibility that the killer or killers lived elsewhere and
   traveled regularly to the area.
5. They included only fibers said to have been used in carpets for residential applications,
   ignoring the fact that the same fiber could be found in many apartments and businesses.
6. They ignored the fact that millions of pounds of the exact same fiber had been sold undyed to
   other manufacturers for use in applications such as car mats.

About the finer probability ration involving the car, Dettlinger points out that “the prosecution
used metro Atlanta figures to show how rare this vehicle would be. This means the Williamses‟
vehicle was not included because it was registered in Muscogee County, which is far from
Atlanta.”

In addition, since four people had been in the Williams home regularly, that made four suspects,
not one. “The prosecution summed up by saying that even though the fibers were common, it is
the combination of fibers which could not be found in any other environment except the Wayne
Williams environment. This gives us four or more suspects, not one, and more importantly:
What about a Laundromat where the environments of hundreds, perhaps thousands of fibers are
mixed and even clogged together in filters? Clifford Jones was killed in the back room of a
Laundromat.




Trace Evidence                                                                                page 6
“Clifford Jones was the final blow to the state‟s fiber case. He was one of only seven who had
the even remotely-unique Wellman fiber. However, both the FBI and the investigating officer
agree with me that Jones was killed by someone other than Williams and the Jones case was not
introduced at the trial even though the defense begged for its submission.”

Clearly the fiber probability ratio was not as impressive as it seemed.

This case was the first to have relied on this type of analysis for pivotal evidence, and several
appeals justices noted that it was too weak: There were no eyewitnesses, weapon, motive,
confession, or clear placement of Williams with any of the victims prior to their deaths. Exactly
what did this evidence corroborate? It was not even that clear that the two victims had been
murdered, and both were adult males, completely unlike any of the young boys used in the ten
“pattern” cases. It seems obvious from the many problems in this case that fiber alone should
not be a deciding factor.

The same can be said for shafts of hair that have only basic distinguishing characteristics.
Nevertheless, trace evidence does have its place, as seen in the following investigation.

                                      Caught by a Hair
In 1990 in Telluride, Colorado, Eva Shoen‟s young daughter found her dead from a single
gunshot to her head. Her husband, Sam, came under suspicion, but he truly appeared to be the
grieving, shocked husband, a victim of random violence. The police were confident they would
solve the case, because the bullet taken from Eva‟s skull had the distinct markings of a particular
type of pistol. However, the case eventually found its way into the cold cases file. There just
were no leads.

Three years later, the Telluride police received a call from a man in Arizona who believed that
his own brother, Frank Marquis, had been the perpetrator. Marquis had once confessed this
crime, but an attempt to trap him during a phone conversation failed. Nevertheless, when the
gun was recovered, an arrest seemed a sure thing. Unfortunately, Marquis had covered his tracks
all too well, including tampering with the barrel of the gun so that the bullet fired from it could
not be matched. All they had on him was a hearsay conversation.

However, tracing Marquis‟ movements indicated that he had indeed been in Telluride during that
weekend for a festival, and that he had a police record for rape. This was the man, the detectives
felt, and they had to find a way to get him. Putting pressure on Marquis‟ travel companion, they
learned that at some point along the road back, Marquis had tossed two bundles out the window
of the car. They suspected that this was the clothing he had worn to commit the crime. Still, it
was a long and winding road between Telluride and the point where Marquis had ended his
journey some four hundred miles away.

Detectives scoured the roadway until they narrowed the possibilities down to four places. As
luck had it, a construction crew had recently moved a pile of dirt, exposing a bundle of clothing
that the dirt had preserved. On the shirt was a single strand of hair, which was examined in the
lab against a sample taken from Eva Shoen. Forensic trace expert Joseph Snyder analyzed the
color and structure, and pronounced them a close match.


Trace Evidence                                                                                 page 7
When the investigators told Marquis of their findings, he confessed. It was a bungled burglary,
he said, indicating his knowledge of the plea-bargaining system. Although the officers in charge
of the case believed that he had in fact planned to rape Eva Shoen and had killed her in the
process, they knew that this would be impossible to prove. Marquis got a sentence of twenty-
four years for manslaughter.

Sometimes a single strand of hair will make all the difference between a case closing down and a
lead that opens it in an entirely new direction.

Is the analysis really that sophisticated or does it just bolster a good guess? To answer that
question, we need to examine the technology.

                                  Hair Evidence Analysis
Like fibers, hair specimens are also understood in forensic research as “class characteristic.” At
best, a hair may have enough similar properties compared with a known sample to be “consistent
with” the sample; it can‟t be said definitively to be a perfect match. While hair samples can be
used to exclude a suspect, as with a Caucasian hair excluding black perpetrators, they can only
be considered as contributing evidence.

In homicide cases, hair is picked up at the scene and is generally collected from several different
parts of the body, including several areas of the scalp. Because different hairs on the same
person can show many variations, the larger the sample for analysis, the better. An average
sample ranges from 24 to 50 pieces, although those samples on which DNA can be done can be
much smaller.

Hair analysis can indicate whether the source is human or
animal, and also whether the source is a member of a particular
race. It can determine if the hair has been dyed, cut in a certain
way or pulled out, and where on the body it was located. In
some cases, evidence of poisoning shows up in the hair. The
hair shaft with a follicle can also offer genetic determinations,
such as blood type or DNA, and since the external layer of the
shaft resists decomposition, it‟s the kind of evidence that has
real staying power.                                                  Human Cells (AP)


Vernon J. Gerberth, in Practical Homicide Investigation, points out that hair (and fiber) evidence
is useful in:

1.   Helping to establish the scope of the crime scene
2.   Placing a perpetrator at a scene
3.   Connecting a suspect with a weapon
4.   Supporting witness statements
5.   Connecting crime scene areas (abduction, vehicle used, dump site)

Forensic analysis of hair centers on color and structure, determined through microscopic
magnification. If the hair has been pulled out, it should include the follicle, and that helps to see


Trace Evidence                                                                                   page 8
the hair‟s full length. The shaft has three forensically relevant layers: the cuticle, cortex, and
medulla. The cuticle has overlapping external scales, which helps in species identification:
Animals are different from humans. Within the cuticle is the cortex, made up of spindle-shaped
cells that contain the color pigment, and the way the pigment is distributed helps to identify hairs
from particular individuals. The center of the shaft is the medulla, which is also valuable for
species differentiation: An animal‟s medullary index (diameter relative to the shaft‟s diameter) is
larger than a human‟s. However, the medulla is often fragmented or interrupted, and may differ
from one hair to another on the same person.

Negroid hairs are kinky, with dense pigments, while Caucasian hairs are generally straight or
wavy, with finer pigmentation. Pigment distribution is also different between the two races. The
hair of an infant or young child tends to be finer than adult hair, but it is difficult to establish
gender from hair samples. Hair that has follicle tissue was probably pulled out, and that tissue
offers the possibility of DNA analysis through the PCR method (which recreates the DNA
molecules).

In the 1950s, a technique called neutron activation analysis became a valuable forensic tool. A
sample such as hair is bombarded with neutrons while inside the core of a nuclear reactor. The
neutrons collide with the components of the trace elements and make them emit gamma radiation
of a characteristic energy level. That way, the scientist can measure every constituent part of the
sample, no matter how small. In a single hair, for example, fourteen different elements can be
identified.

The first case to utilize neutron activation analysis was the 1958 murder of 16-year-old Gaetane
Bouchard in Canada. Her former boyfriend, John Vollman, lived across the border in Maine and
he was seen with her just before she was discovered dead. Flakes of paint from the place where
they had been together were matched to his car. Also, the victim‟s color of lipstick was found on
candy in his glove compartment. However, it was the strands of hair found clasped in the
victim‟s hand that ultimately convinced the jury. These were matched to Vollman via a ratio of
sulfur radiation to phosphorus, which was closer to his ratio than hers.

As forensic science advances with computers and increasingly more accurate means of detecting
the component parts of small samples, trace evidence may soon play even more significant roles.
As it is, the more trace evidence an investigator can collect at a crime scene, the better the
chances of making a case.

Although hair and fiber are currently the most frequently analyzed trace evidence, there are other
types that ought to be noted. A few have offered important clues for solving a crime.

                             Other Types of Minute Traces
Crime scene examiners are looking for anything, no matter how minute, that appears to be
foreign to the place. Aside from hair and fiber, along with other bodily secretions, there are
more items that can come under scrutiny. Any object or substance becomes evidence if it can be
identified as not naturally belonging to a scene and then linked with a suspect. Databases for
comparison are maintained in most large forensic labs, with the most extensive collection for
many types of trace evidence located at the FBI.


Trace Evidence                                                                               page 9
Among the most common substances for trace analysis are:

Glass: When product tampering made national news in the 1980s, some consumers placed glass
       fragments in jars of baby food in the hope of a monetary settlement. Analysis of the
       fragments indicated that each type of contaminant was from a different source, so this
       “crime spree” was unlikely to have been the work of a lone tamperer. Glass is a
       solidified liquid that has unusual properties. If a perpetrator smashes glass, some tiny
       slivers will adhere to his clothing, even after it has been cleaned. Glass identification
       involves a complex microscopic examination that measures the “refractive index,”
       calculated from the angle at which a ray of light hits the surface. Pieces of glass may also
       be analyzed through spectrography or neutron activation, and glass shatter patterns have
       provided important clues about how an event took place.

Dirt/dust: Particles picked up on a suspect‟s clothing can sometimes reveal where he or she has
       been, and the same goes for where a corpse has been, which helps to determine whether a
       murder victim has been moved. Plant spoors, insects, and other microorganisms that are
       revealed under the microscope provide clues. Dust particles generally yield something
       about their origins, whether from a concrete floor, bricks, cement, or a particular room.
       They might offer leads about where someone lives or works. The 1960 murder of 8-year-
       old Graeme Thorne was partly solved by traces of pink mortar found on his clothing. A
       house with pink mortar was located, and further evidence was found to close the case and
       convict the killer.

Palynology: This is the study of palynomorphs, or pollen data, trapped in or found on materials
      associated with a crime. Because of their predictable production and dispersal rates in
      specific regions, they can help to link a suspect to the scene of a crime. In fact,
      palynologists believe that both legal teams missed a bet in the O.J. Simpson case by
      failing to look into pollen. If Simpson was present at the crime scene, and had hidden in
      the bushes as was suggested, his clothing might have picked up pollen spoors. If not,
      then this would have been important evidence in his defense. The earliest cases in this
      field were in the sixties. A 1969 murder investigation in Sweden used the presence of
      pollen in the dirt found on the body to show that she had been killed in a spot other than
      where she was found. In an Austrian case, mud on a murderer‟s boots linked him to a
      crime scene, and he confessed. One detective even found pollen in the grease of a killer‟s
      gun, and another found pollen in the ink of a document that demonstrated that it was a
      forgery.

Paint: The techniques used for glass analysis are also employed for paint chips. Chips from
       cars can be compared to samples in the National Automotive Paint File, which holds
       more than 400,000 samples. Undercoats help to narrow down the possible
       manufacturers. Also the shape of a chip can be matched to an area where a chip is
       missing, and its chemical constituents can be analyzed via releasing the gases and using
       gas chromatography. That creates identifying characteristics for each layer and
       establishes points of comparison. A trace of yellow paint was found in a spot where a
       rapist had hidden his car was traced to a specific model. When a suspect was located
       through a computer database that included those cars, his vehicle showed the scrape at



Trace Evidence                                                                             page 10
       the appropriate height. With the police on his trail and evidence accumulating, he
       confessed and was sent to prison.

Seeds: In the 1960 murder of Graeme Thorne, seeds from a rare type of cypress told
       investigators that the body had been moved from the murder site. A cypress tree found in
       a garden of a house that also matched mortar found on the body pointed the police in the
       right direction. Further evidence built a solid case against Stephen Bradley, who was
       convicted. Like pollen analysis, knowledge of plant life peculiar to certain areas can
       offer important information for making decisions in criminal investigations.

Other types of evidence and modes of analysis may be lumped under the category of “trace
evidence,” but the information presented here shows the basic principles: Collect apparently
foreign matter from a crime scene or body, and use the best method for measuring the most
clearly identifying characteristics. That information, when compared with similar substances
associated with a suspect, can corroborate other types of evidence and help to build a case. Right
or wrong, juries have convicted on trace evidence alone, and responsible forensic investigators
will try to make sure that it truly proves what they claim.




Trace Evidence                                                                              page 11

				
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