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| The environment
offers many clues that, during the course of a day,
we often overlook or take for granted. The dust and
dirt that accumulates on the bottom of our shoes, minerals,
fibres and seeds provide important clues about the crime,
as well as the suspect. These minute clues can often
point to the criminal's hobbies, occupation, habits
and movements and are often helpful in guiding an entire
investigation. |
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Select a topic from below to learn more:
--> Collection
--> Basic
comparison
--> Seeds
and pollen
--> Soil
and dust
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| Copyright
2004-2005 Thinkquest Team 00206 |
| Collection |
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| Like
the collection of trace evidence, dirt and dust
from a crime scene are collected using tape or
a forensic vacuum to lift the sample from its
surroundings. Once taken to a forensic laboratory,
a careful analysis of the dust and dirt samples
can be conducted under controlled conditions.
Large particles in the sample are extracted, making
the overall sample analysis clearer. A complete
soil analysis is rare because of time consumption,
but may be necessary depending on the case involved.
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Powders collected may be analysed to reveal any
illicit drugs. Photo courtesy of www.free-stock-photos.com.
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| Copyright
2004-2005 Thinkquest Team 00206 |
| Basic
Comparison |
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| Less time consuming
analyses are likelier to be done when the simply matching
of mud samples is required. A direct comparison of the
two samples is conducted, with investigators looking
for aspects such as colour similarities, pH
levels and the variety and size of the particles
found in the sample. For example, mineral particles
will have traces of the rock from which they were derived,
such as quartz and limestone, while grains of sand have
distinctly different shapes if say, one comes from the
ocean and the other from a desert. |
| Copyright
2004-2005 Thinkquest Team 00206 |
| Seeds
And Pollen |
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Biological
matter in a sample of soil such as leaves, compost,
pollen, seeds and spores from fungi are analysed
also, for it too, can pinpoint the sample's area
of origin. Seeds from plants which are only found
in a certain areas provide a guide to tracking
down the place where the dirt originated and the
pollen of plants are also used in the same way,
for example, in narrowing down a search for a
buried body by using a sample of soil found on
a suspect's clothing or car. |
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| Seeds and pollen also
provide accurate chronological details because most
plants only shed pollen or seeds at certain times of
the year. This information can not only prove that a
suspect was in a certain area at the time, but also
what season and time of the year it may have been. Most
labs contain computer recorded databases of biological
matter, which when attached to a scanning
electronic microscope, are able to find identify
certain particles in a sample with those already on
the database. |
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(Above ) Pollen of rare flowers are useful clues. Photo
courtesy of www.imageafter.com. |
| Soil
And Dust |
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Soils samples are analysed by biologists and mineralogists,
who provide investigators with details of the areas
where particular plants, seed and pollen may be found.
The analysis of soil is used mainly for the purpose
of finding a certain place, usually a scene of crime.
Dust, is equally as helpful as soil samples, as dust
is different in every house and is unique to every
room of a house. Samples of dust located in the bathroom
often contain cosmetics, and powder while samples
found in the kitchen contain flour and spices. Animal
hair, skin cells, dust mites and fibres form clothing
and carpets also contain evidence unique to a certain
house.
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*The differences between soil composition are very evident
in the samples above. Photos courtesy of www.imageafter.com.
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