Impression Evidence Collection in CSI Investigations
CSI Unit Training Materials
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T. Tomm Updated 2023
https://sciencespot.net
Teacher Note: You may
want to complete the
Case Study: Tourist
Trap prior to this lesson
and the bite mark
activity.
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The student digital slides for this unit are available ataringuQp2Rx2B4rqWOKOhk4m9SwZ0MVWmYw/edit?usp=shhttps://docs.google.com/presentation/d/1Ray7CFPod01Uy
IMPORTANT: Make a copy of the student notebook
before you assign it on your LMS. It is view-only and I am
not able to approve access for your students.
The FULL digital notebook (with all the slides for the digital
lessons and activities) is available at
.
It is set up for standard paper (8.5x11) in landscape mode
for easier printing when needed. Paper versions are
available for this unit on my Forensic Science page athttps://sciencespot.net/Pages/classforsci.htmlyuUxiEsSM2m4YOAtIlfmD4O4YsLdPI/edit?usp=sharinghttps://docs.google.com/presentation/d/14eIEiGacRXMsD
A DRAFT of the general outline of the digital lessons (with
corresponding slide #s for the student notebook) is
available at
. It is based on 44-minute class
periods with 7
th
& 8
th
grade students.9mA/edit?usp=sharinguHQPXDKOxmZXtU_gxy9dphEuyC1P4jzP-https://docs.google.com/document/d/15wxjmL-
Preview presentations before using with your classes as
many slides have animations and links you will need to
use.
I do Science Starters at the beginning of each class
period. A collection of starters for Forensics is available
on my lessons plans page at
.https://sciencespot.net/Pages/classforsci.html
IMPRESSION EVIDENCE
can be defined as
OBJECTS
or
MATERIALS
that have retained the
characteristics of other objects through direct
CONTACT
.
SHOEPRINTS
,
TOOL MARKS
,
TIRE TRACKS
,
BITE MARKS, and
RIFFLING
marks on a bullet
are several examples of impression evidence.
The
QUALITY
of the impression depends on:
The
OBJECT
making the impression
The
HARDNESS
of the
surface conditions, and
What type of
MATERIAL
makes up the surface
(soil, mud, dust, concrete, grass, skin, etc.)
Images: http://upload.wikimedia.org/wikipedia/commons/archive/6/61/20070917141644!Shoeprint(forensic).jpg and
http://www.topmark.co.nz/images/content/tmpics01/gallery-s/SilipressionTeethMold.jpg
What is impression evidence?
2-Dimensional (2D):
Documented using photography to show TWO dimensions (length &
width or width & height)
Rulers may also be used to document exact dimensions.
Impressions may be dusted with powder to be photographed or lifted
with tape. They may also be collected using an electrostatic dust
lifting process.
Shoeprint:
http://www.forensicsciencesimplified.org/fwtt/how.html
How is impression evidence collected?
Tire Track:
https://www.youtube.com/watch?v=dhkSlJadfPs
Shoeprint:
http://www.forensicsciencesimplified.org/fwtt/how.html
Images:
http://www.evidentcrimescene.com/cata/cast/dscasting.html
CLASS
Characteristic that shows the
class or group
a
material belongs.
E
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:
•
Tire tread pattern matches to a
brand
/type of tire
•
Teeth or bite marks matches to a specific
species
of animal
•
Paint chip from a tool may help us identify the
manufacturer of the tool
INDIVIDUAL
C
haracteristics that match of evidence to
ONE
specific item or person
.
E
x
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s
:
•
Wear pattern on a shoe print matches
a suspect’s shoe.
•
Bite mark shows specific locations of teeth that can be matched to
a
suspect’s
dental profile
•
Break in the end of a screwdriver matches
a spot
in the wood where it was
used to pry open a door
Class vs. Individual Characteristics
Footprint
Evidence
____ Wear pattern on a shoe print matches a suspect’s shoe (&
his/her walking pattern)
____ Paint chip from a tool matches the type of red paint used
on Tools R Us tools.
____ Tire tread pattern matches patterns used on a
Hoosier 4-
Ply Super Turf tire.
____ Broken corner on a screwdriver matches a mark left on a
wooden doorway at a crime scene
____ Teeth or bite marks matches to a specific breed of dog.
____ Bite mark shows specific locations of teeth that can be
matched to a suspect’s dental profile.
Directions: Use what you learned from the previous slide to
identify each example as either C (class) or I (individual).
Identify each example as either C (class) or I (individual).
____ Wear pattern on a shoe print matches a suspect’s shoe (& his/her
walking pattern)
____ Paint chip from a tool matches the type of red paint used on
Tools R Us tools.
____ Tire tread pattern matches patterns used on a
Hoosier 4-Ply
Super Turf tire.
____ Broken corner on a screwdriver matches a mark left on a
wooden doorway at a crime scene
____ Teeth or bite marks matches to a specific breed of dog.
____ Bite mark shows specific locations of teeth that can be matched
to a suspect’s dental profile.
ANSWER
KEY
Part B: Bite Mark Evidence
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•
TYPE
of bite mark (human or animal)
•
TEETH
characteristics
(position, dental work ,
wear patterns, etc.)
•
TIME SINCE BITE –
The color of the area helps to estimate how
long ago the bite occurred (old or recent bite)
•
DNA
- Swab for saliva or blood for
DNA testing.
•
LOCATION
- Marks can be left on a
victim’s skin or other objects, such as
Styrofoam cups, gum, or foods.
Images: http://www.forensicdentistryonline.org/Forensic_pages_1/currentopic1.htm, http://www.trestonedental.co.uk/images/0303.jpg
Bite Mark Evidence Video
Time to create some evidence …
Make an Impression
1 – Label one side
MAXILLA
(top jaw) and
the other
MANDIBLE
(lower jaw).
2 - Fold the
Styrofoam plate
in half.
3 – Gently bite down on the plate to leave your
bite mark impression.
4 - Place a sheet of
plastic film
over the
impression and use a permanent marker to
recreate the pattern to match that of your bite
mark.
Maxilla
Mandible
http://forensicfact.files.wordpress.com/2008/05/cast_negative_resized_copy.jpg
A closer look at bite mark evidence …
Analyze your bite mark and compare with
your group.
How does the width of your bite mark compare
to the depth?
Do you have the same number of individual
tooth impressions as your group mates?
What other details do you observe that would
make it easy to identify as your bite mark?
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http://forensicfact.files.wordpress.com/2008/05/cast_negative_resized_copy.jpg
Answer the questions on your notes.
What CLASS characteristics do you see in your bite mark?
What INDIVIDUAL characteristics do you see in your bite mark?
List 3 characteristics.
http://forensicfact.files.wordpress.com/2008/05/cast_negative_resized_copy.jpg
Possible answers would include the different types of
human teeth (incisors, canines, molars) and approximate
age (if molar impressions are present).
Possible answers would include missing teeth (baby teeth
or other reasons), angles/slanted impressions, marks from
braces, width & depth of bite mark, and tooth damage
(chips, broken teeth, etc.)
#2 - Bite Mark Challenge - Follow your teacher’s directions to
test each material. Complete the chart with your quality rating
and observations.
Quality
1 = Poor to 5 = Excellent
What materials worked the best? Why?
What else could we use?
You may substitute
other candy for these
items, but I recommend
keeping the circus
peanut. It usually ends
up with the best rating!
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Tire tracks are important in forensic investigations
and are usually found in road
accident
scenes or may
provide clues at
crime scenes
.
Investigators may make
ink prints
of a tire or plaster
casts
of a track. They will also take
photographs
that can later be used to prove a match.
Features to analyze
:
•
Tread
pattern and
size
(width & depth) can help
investigators identify the type of
vehicle
that left
them
•
Use tire
databases
to determine the brand and
model of the tire that left the impression.
•
Unique characteristics due to the
wear pattern,
damage,
or material
defects
to help match it to a
specific
vehicle
Images: http://www.suite101.com/view_image.cfm/454216, http://www.ronsmithandassociates.com/FWTTS.htm.
Part C: Tire Track Evidence
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Video Link: https://edpuzzle.com/media/5ae084f8cf5572411ed5ca8d
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Forensic Science Activity
http://pro.corbis.com/images/CB001940.jpg?size=572&uid={D27A89DF-00BB-4028-AA57-7A908AF0511D}T. Trimpe 2007 http://sciencespot.net
Tire Track Lab
Your group will need to document the
tread patterns for each vehicle.
Step 1
: Get a large piece of white paper from your teacher. You will also need a pen or pencil.
Step 5:
Gently
roll each car on the white paper for a length of 5-6” and
label
the tracks with
the correct letter.
Caution
: You will want to apply enough pressure to get a good impression, but not too hard that you
cause damage to the vehicle, its tires, or the ink pad.
Step 6:
Roll each car on a piece of paper towel to remove excess ink and then wait quietly for
the teacher to say to “rotate” before you go to the next station.
Step 2:
Fold the paper into thirds as
demonstrated by your teacher.
Step 3:
Divide each column into 6 spaces for
a total of 18 spaces.
Step 4:
At each station, g
ently
roll each car
over the ink pad
several times
to cover all the
sides of the tires.
Teacher Note: For this activity I raided my son’s Hot
Wheels box to find 18 different types of vehicles. I
labeled them with letters using a label maker. I
used ink pads (harder ink instead of those with a
sponge) to make “evidence” samples.
I selected 8 of the best samples to use for the
challenge activity. I organized digital pictures of
them on a page, which was laminated to use in the
class activity.
Go to
https://sciencespot.net/Media/FrnsScience/ImpEvi_
Tiretracksinfo.pdf
for more information.
Step 7: Cut apart the tread samples so you have 18 strips.
Organize into at least
3
different groups.
Step 8: Analyze the tire tracks to identify unique characteristics
and use a highlighter to mark each characteristic you find.
Features to analyze:
•
Tread
pattern
•
Width
&
depth
of the tread pattern
•
Unique characteristics due to the
wear pattern, damage,
or
defects
Answer the question on your notes based on the types of
features you observed highlighted.
Work with your partner to identify the 8 tracks shown on the
challenge worksheet.
Compare the tracks you made earlier and match them to the
suspect tracks on the worksheet.
Once you have identified all the cars, have your answers checked
by your teacher. Keep trying until you have them all correct!
Tire Track Challenge
Go to
https://sciencespot.net/Media/FrnsScience/I
mpEvi_Tiretracksinfo.pdf
for more
information.
How many of the real tire tracks can you identify?
(1)
Examine the samples located around the room.
NOTE: You are not allowed to move them!
(2)
Examine the ink prints on the back cabinets.
(3)
Write down the numbers that match each ink print
in the box on your worksheet.
(4)
You will have 10 minutes to match as many as you
can before we go over the answers!
REAL DEAL CHALLENGE
Teacher Note: I obtained samples of real tire treads from a local tire shop. They
labeled the back with the brand of tire. I used a paint roller and ink to make prints.
The prints were laminated and displayed around the classroom. Students had
time to examine the real tires and try to match it to a print.
Go to
https://sciencespot.net/Media/FrnsScience/t
iretracksinfo.pdf
for more information.
Impression evidence plays a crucial role in investigations, including shoeprints, tool marks, tire tracks, bite marks, and riffling marks on bullets. This evidence can be collected in 2D using photography or tape lifts, and in 3D through casting methods. Differentiating between class and individual characteristics is essential in linking evidence to suspects or items. Learn how to identify and gather impression evidence effectively for forensic analysis.
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Presentation Transcript
CSI Unit Training Materials Impressive Evidence Complete the slide as we watch the video. You will use the information to determine which view (investigators or detectives) you believe to be the most reliable. T. Tomm Updated 2023 https://sciencespot.net
What is impression evidence? IMPRESSION EVIDENCE can be defined as OBJECTS or MATERIALS that have retained the characteristics of other objects through direct CONTACT. SHOEPRINTS, TOOL MARKS, TIRE TRACKS, BITE MARKS, and RIFFLING marks on a bullet are several examples of impression evidence. The QUALITY of the impression depends on: The OBJECT making the impression The HARDNESS of thesurface conditions, and What type of MATERIAL makes up the surface (soil, mud, dust, concrete, grass, skin, etc.) Images: http://upload.wikimedia.org/wikipedia/commons/archive/6/61/20070917141644!Shoeprint(forensic).jpg and http://www.topmark.co.nz/images/content/tmpics01/gallery-s/SilipressionTeethMold.jpg
How is impression evidence collected? 2-Dimensional (2D): Documented using photography to show TWO dimensions (length & width or width & height) Rulers may also be used to document exact dimensions. Impressions may be dusted with powder to be photographed or lifted with tape. They may also be collected using an electrostatic dust lifting process. Shoeprint: http://www.forensicsciencesimplified.org/fwtt/how.html
3-Dimensional (3D): Documents THREE dimensions (length, width, & height/depth) of a piece of evidence Casts are made to show depth, which involves using dental cement (or a similar substance) to preserve the dimensional characteristics of the print. Evidence may also be photographed with rulers or other objects to document dimensions Tire Track: https://www.youtube.com/watch?v=dhkSlJadfPs Shoeprint: http://www.forensicsciencesimplified.org/fwtt/how.html Images: http://www.evidentcrimescene.com/cata/cast/dscasting.html
Class vs. Individual Characteristics CLASS material belongs. Characteristic that shows the class or group a Examples: Tire tread pattern matches to a brand/type of tire Teeth or bite marks matches to a specific species of animal Paint chip from a tool may help us identify the manufacturer of the tool Footprint Evidence INDIVIDUAL specific item or person. Characteristics that match of evidence to ONE Examples: Wear pattern on a shoe print matches a suspect s shoe. Bite mark shows specific locations of teeth that can be matched to a suspect s dental profile Break in the end of a screwdriver matches a spot in the wood where it was used to pry open a door
Directions: Use what you learned from the previous slide to identify each example as either C (class) or I (individual). ? ____ Wear pattern on a shoe print matches a suspect s shoe (& his/her walking pattern) ? ____ Paint chip from a tool matches the type of red paint used on Tools R Us tools. ? ____ Tire tread pattern matches patterns used on a Hoosier 4- Ply Super Turf tire. ? ____ Broken corner on a screwdriver matches a mark left on a wooden doorway at a crime scene ? ? ____ Teeth or bite marks matches to a specific breed of dog. ____ Bite mark shows specific locations of teeth that can be matched to a suspect s dental profile.
Identify each example as either C (class) or I (individual). I ____ Wear pattern on a shoe print matches a suspect s shoe (& his/her walking pattern) C ____ Paint chip from a tool matches the type of red paint used on Tools R Us tools. C ____ Tire tread pattern matches patterns used on a Hoosier 4-Ply Super Turf tire. I ____ Broken corner on a screwdriver matches a mark left on a wooden doorway at a crime scene C I ____ Teeth or bite marks matches to a specific breed of dog. ____ Bite mark shows specific locations of teeth that can be matched to a suspect s dental profile.
Part B: Bite Mark Evidence WHAT CLUES CAN WE GET FROM A BITE MARK? Bite Mark Evidence Video TYPE of bite mark (human or animal) TEETH characteristics(position, dental work , wear patterns, etc.) TIME SINCE BITE The color of the area helps to estimate how long ago the bite occurred (old or recent bite) DNA - Swab for saliva or blood for DNA testing. LOCATION - Marks can be left on a victim s skin or other objects, such as Styrofoam cups, gum, or foods.
A closer look at bite mark evidence Make an Impression Maxilla 1 Label one side MAXILLA (top jaw) and the other MANDIBLE (lower jaw). 2 - Fold the Styrofoam plate in half. Width 3 Gently bite down on the plate to leave your bite mark impression. Depth 4 - Place a sheet of plastic film over the impression and use a permanent marker to recreate the pattern to match that of your bite mark. Mandible Time to create some evidence http://forensicfact.files.wordpress.com/2008/05/cast_negative_resized_copy.jpg
Maxilla Analyze your bite mark and compare with your group. How does the width of your bite mark compare to the depth? Width Do you have the same number of individual tooth impressions as your group mates? Depth Mandible What other details do you observe that would make it easy to identify as your bite mark? http://forensicfact.files.wordpress.com/2008/05/cast_negative_resized_copy.jpg
Answer the questions on your notes. What CLASS characteristics do you see in your bite mark? Possible answers would include the different types of human teeth (incisors, canines, molars) and approximate age (if molar impressions are present). What INDIVIDUAL characteristics do you see in your bite mark? List 3 characteristics. Possible answers would include missing teeth (baby teeth or other reasons), angles/slanted impressions, marks from braces, width & depth of bite mark, and tooth damage (chips, broken teeth, etc.) http://forensicfact.files.wordpress.com/2008/05/cast_negative_resized_copy.jpg
#2 - Bite Mark Challenge - Follow your teachers directions to test each material. Complete the chart with your quality rating and observations. Quality 1 = Poor to 5 = Excellent Candy Quality Observations Orange Slice Tootsie Roll Airhead Swedish Fish Circus Peanut What materials worked the best? Why? What else could we use? NOTE: As with any lab involving food, be aware of any food allergies that may be a concern with your students.
Part C: Tire Track Evidence Tire tracks are important in forensic investigations and are usually found in road accident scenes or may provide clues at crime scenes. Investigators may make ink prints of a tire or plaster casts of a track. They will also take photographs that can later be used to prove a match. Features to analyze: Tread pattern and size (width & depth) can help investigators identify the type of vehicle that left them Use tire databases to determine the brand and model of the tire that left the impression. Unique characteristics due to the wear pattern, damage, or material defects to help match it to a specific vehicle Images: http://www.suite101.com/view_image.cfm/454216, http://www.ronsmithandassociates.com/FWTTS.htm.
Directions: Complete the notes as you watch the video. Video Link: https://edpuzzle.com/media/5ae084f8cf5572411ed5ca8d
United Streaming: The Value of Evidence Click to reveal answers Part A: Complete this worksheet as you watch the video. PHYSICAL 1. The job of the Forensic Science Unit is to collect ____________ evidence. PHOTOGRAPHED 2. To document a tire track, it is first ______________________ and then ___________ are made using dental cement that is poured into a metal form. CASTS LIGHT 3. Investigators use a high-powered _____________ to trace the path to the victim. The light shines at ____________________ that cause materials to fluoresce and ________________ goggles help make evidence stand out sharply. WAVELENGTHS ORANGE 4. Evidence that is collected at a crime scene is analyzed by a ___________, who goes through the debris that is collected at a crime scene. CHEMIST (Or other specialists) CARPET 5. ____________ fibers are valuable clues because they can link suspects to a specific location.
6. The tire track expert studies the photographs taken at the crime scene to examine the tread _____________ to determine what kind of vehicle uses that kind of a tire. PATTERNS 7. Tire treads are made up of geometric shapes called __________. The key to tire identification ______________ in pitches. They also examine tiny cuts on the surface called _______ that were molded into the tire by small metal teeth. PITCHES is to match DIFFERENCES SIPES EVIDENCE 8. The final pieces of _______________ needed for an airtight case was obtained by investigators offering a dog bathing service. During the bath, investigators gathered some dog _________ and also got carpet _________ from the living room, which matched those found at the crime scenes. HAIRS FIBERS
Tire Track Challenge Forensic Science Activity http://pro.corbis.com/images/CB001940.jpg?size=572&uid={D27A89DF-00BB-4028-AA57-7A908AF0511D} T. Trimpe 2007 http://sciencespot.net
Your group will need to document the tread patterns for each vehicle. Tire Track Lab Teacher Note: For this activity I raided my son s Hot Step 1: Get a large piece of white paper from your teacher. You will also need a pen or pencil. Step 2: Fold the paper into thirds as demonstrated by your teacher. Step 3: Divide each column into 6 spaces for a total of 18 spaces. Step 4: At each station, gently roll each car over the ink pad several times to cover all the sides of the tires. Step 5: Gently roll each car on the white paper for a length of 5-6 and label the tracks with the correct letter. Caution: You will want to apply enough pressure to get a good impression, but not too hard that you cause damage to the vehicle, its tires, or the ink pad. Step 6: Roll each car on a piece of paper towel to remove excess ink and then wait quietly for the teacher to say to rotate before you go to the next station.
Step 7: Cut apart the tread samples so you have 18 strips. Organize into at least 3 different groups. Step 8: Analyze the tire tracks to identify unique characteristics and use a highlighter to mark each characteristic you find. Features to analyze: Tread pattern Width & depth of the tread pattern Unique characteristics due to the wear pattern, damage, or defects Answer the question on your notes based on the types of features you observed highlighted.
Tire Track Challenge Work with your partner to identify the 8 tracks shown on the challenge worksheet. Compare the tracks you made earlier and match them to the suspect tracks on the worksheet. Once you have identified all the cars, have your answers checked by your teacher. Keep trying until you have them all correct! Ready? Set? GO!
REAL DEAL CHALLENGE How many of the real tire tracks can you identify? (1) Examine the samples located around the room. NOTE: You are not allowed to move them! (2) Examine the ink prints on the back cabinets. (3) Write down the numbers that match each ink print in the box on your worksheet. (4) You will have 10 minutes to match as many as you can before we go over the answers! Teacher Note: I obtained samples of real tire treads from a local tire shop. They labeled the back with the brand of tire. I used a paint roller and ink to make prints. The prints were laminated and displayed around the classroom. Students had time to examine the real tires and try to match it to a print.
