Transcript Ballistic Trajectory Lab and Notes

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Pattern evidence is generally created by
the contact of two surfaces (persons,
vehicles, or objects). Result in the
formation of:
◦ Impressions
◦ Imprints
◦ Markings
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Contact types:
◦ Static (stationary)
◦ Dynamic (moving)
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Impression types:
◦ Two dimensional or three dimensional
Individualization patterns:
 Individualization patterns are those which
have the potential to be associated with an
item or person responsible for it
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Fingerprints
Palm prints
Footprints
Handwriting
Toolmarks
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Conducted by the forensic firearms
examiner at the crime lab.
Involves function and operation of the
weapon, association of weapon, bullets
and casings.
Often involves evaluation of ejection
patterns and gun shot residue range
determinations.
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Conducted by the forensic pathologist.
Involves defining the path of a bullet
through the body, the associated damage
and differentiating entry from exit
wounds.
Also includes issues of range
determinations.
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Conducted by the crime scene analyst
most often, may involve the firearms
examiner.
Involves defining the path of a bullet
through the scene by evaluating various
scenes aspects, such as penetrations and
perforations, casings and known positions
of the victim or shooter.
Ultimately it defines possible and
impossible scenarios for bullet
trajectories.
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Primary concern of
external ballistics is
evaluating bullet
defects.
Trajectory kits are used
to do this, they
include:
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trajectory rods.
centering guides.
angle finders.
in some cases lasers.
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Verify the defect is a
bullet hole.
This is done based on:
◦ visual examination.
◦ presence of bullets or
remnants.
◦ chemical presence of lead
or copper.
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Insert the rod into a
perforating defect.
Use centering guides
to level the rod in the
defect.
Lack of centering
guides can affect the
angle significantly.
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Centering guides are
used on both sides of
the perforation.
Guides are not forced
into the defect and are
held in place by small
rubber grommets.
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Angle finder used to
document the angle of
the trajectory.
Documentation
includes identifying the
exact position of
defects.
Rods can be extended
several feet without
sagging.