1. what is impression evidence? -...

T. Trimpe 2009

1. What is impression evidence?

Impression evidence can be generally defined as

characteristics of other objects through direct

against another material with enough ______________

Shoeprints, ______________ marks, tire ______________

examples of impression evidence.

Impressions may be found in or on many different types of

depends on the object making the impression

type of material it is (soil, mud, dust, concrete, grass, skin, etc.)

2. Collection Methods

Investigators analyze the impression evidence to find unique

objects found in a suspect’s possession to evidence at a crime scene.

Collection of impression evidence can be accomplished using several methods:

2-D: This type of impression is documented using

fingerprint ______________ to be photographed or lifted with

collected using an ______________

3-D: This type of impression can be documented using

involves using dental stone to preserve the dimensional characteristics of the

3. Tire Track Evidence

Tire tracks are important in forensic investigations and are usually found in road

and escape ______________ of other crime scenes. Tracks help investigators identify the type of

left them. Investigators may make ______________

track. They will also take ______________

Features to analyze:

• ______________ pattern

• ______________ & ______________

• Unique characteristics due to the ______________

T. Trimpe 2009 http://sciencespot.net/

Name __________________________________

can be generally defined as ______________ or ______________

characteristics of other objects through direct ______________. Impressions are created when one object is pressed

______________ to leave an impression of the object.

______________, bite marks, and marks on a fired ______________

Impressions may be found in or on many different types of ______________. The ______________

depends on the object making the impression and the ______________ conditions, such as how hard or soft it is and what

type of material it is (soil, mud, dust, concrete, grass, skin, etc.)

Investigators analyze the impression evidence to find unique ____________________ to link shoes, tires, tools, and other

objects found in a suspect’s possession to evidence at a crime scene.

Collection of impression evidence can be accomplished using several methods:

This type of impression is documented using ______________. Some impressions may be dusted

to be photographed or lifted with ______________

______________ dust lifting process.

: This type of impression can be documented using ______________ as well as by ______________

to preserve the dimensional characteristics of the print.

Tire tracks are important in forensic investigations and are usually found in road ______________

f other crime scenes. Tracks help investigators identify the type of

______________ ______________ of a tire or ______________

______________ that can later be used to prove a match.

______________ of the tread pattern

______________ pattern or ______________

Name __________________________________

______________ that have retained the

Impressions are created when one object is pressed

______________ are several

______________ of the impression

conditions, such as how hard or soft it is and what

to link shoes, tires, tools, and other

. Some impressions may be dusted with

______________. They may also be

______________, which

______________ scenes or in the access

f other crime scenes. Tracks help investigators identify the type of ______________ that

______________ ______________ of a


4. Tool Mark Evidence

Certain ______________ or ______________ may be left on a tool when it is made or used, which can be used to find

matches between evidence at a crime scene and tools or objects found at a suspect’s home.

Tool marks can be classified two ways: ______________ or ______________.


• ______________ of the impression

• Ridges or striation ______________

• ______________, such as nicks and chips

• ______________ chips or ______________ shards left on a tool

5. Shoe Print Evidence

Investigators can analyze a shoe print to determine its ______________, or the type and brand of shoe. They will also

look for ______________ characteristics, such as ______________ ______________ and specific ______________ or

______________.

Databases of shoe prints are available for investigators to help them determine the ______________ of shoe to provide

leads for a case.

Depending on the quality of the impression, investigators may be able to determine a person’s ______________ (walking

vs. running) as well as estimate the ______________ of a person based on the impression’s depth.


• ______________ patterns, size, and depth

• ______________ patterns caused by the way a person walks

• Material defects or ______________ (nicks, cuts, etc.)

• Other ______________ materials, such as soil, tar, rocks, and paint that would indicate where a person has been

6. Bite Mark Evidence

Investigators can analyze ___________ ___________ for characteristics to help them identify victims or suspects as well

as to exclude others. Marks can be left on a victim’s ______________ or other ______________, such as Styrofoam

cups, gum, or foods. ______________ or ______________ may be left behind that can be tested for ______________.

Dental records including ____-_______ can also provide useful information, especially when attempting to identify a

victim.


• ______________ of bite mark (human or animal)

• Characteristics of the ______________ (position, evidence of dental work, wear patterns, etc.)

• ______________ of area to estimate how long ago the bite occurred (old or recent bite)

• Swab for ______________ ______________ for DNA tests

CSI Tool Mark ChallengeIdentify each impression based on your observations of the sample tools.


CSI Tool Mark Challenge #1Identify each impression based on your observations of the sample tools.

#1 Identify each impression based on your observations of the sample tools.

CSI Tool Mark ChallengeIdentify each impression based on your observations of the sample tools.


CSI Tool Mark Challenge #2Identify each impression based on your observations of the sample tools.

#2 Identify each impression based on your observations of the sample tools.


Tool Mark ChallengeTool Mark ChallengeTool Mark ChallengeTool Mark Challenge Teacher Information

Materials Needed: 12 tool (2-4 different types) - Choose a variety of styles and sizes

NOTE: You will want at least 3 of the same tool, but with different characteristics. For example, choose 3 flat

head screwdrivers in various thicknesses and head widths. I happened to have enough spare screwdrivers and

pliers to make up a set with 6 of each one for this activity.

Copies of Tool Mark Challenge worksheet

Rulers

Molding Clay (Dark blue or green works well)

Small plastic plates

Preparation:

1 – Label the tools with numbers and use clay to make impressions for your challenge. If you are going to use the clay

impressions for the challenge, place each one in a plastic bag and label with a letter.

NOTE: I used a digital microscope camera (Dino Lite) to photograph the impressions made by each of the tools and

choose the best ones for the challenge. I printed several copies of the challenge on card stock and laminated them to keep

them in good condition. My "Tool Marks Challenge" is available on the Forensic Science page of my website in the

Impression Evidence section.

2 - For the student groups, I set up 6 stations in my room with 2 tools at each station along with rulers, a slab of clay, and

a plastic plate. The students work in groups and have approximately 5 minutes to document the 2 tools before they rotate

to a new station. They also have an extra time at the end of class to take another look at the tools as well as a little time at

the start of the next class period.

3 - Make copies of the Tool Marks worksheet (one per group.)

Activity:

Day 1:

1 - Give each group a copy of the worksheet and show the first part of the Tool Marks Challenge presentation The

presentation is available on the Forensic Science page of my website in the Impression Evidence section.

2 - Allow time for the groups to visit each of the 6 stations to examine and document each of the tools and its impression.

I tell my students that they may write anything on their worksheet that might help them identify the tool during the

challenge - this includes sketches and traced outlines of the tools.

Day 2:

1 - Pass out the challenge pages - one for each group.

2 - Have the groups use their notes from the previous day to match the tools to the tool mark impressions. You may want

to have the tools and clay available as some groups may want to recheck a few of them.

3 – Allow time for the students to identify the impressions and then check their answers.

NOTE: I have several identification labs that are races – the first group done receives a prize and bragging rights. I

require the groups to have an answer for each item before they can check their answers the first time. I mark the ones

that are incorrect and the students keep working until they get them all correct (or until at least half of the groups are

finished.)

4 - Discuss how tool marks can be used to solve crimes.


Group Members: ________________________________________________________________________

Goal: Your group will need to examine and document the tool marks made by each of the 12 tools.

At each station, you will need to:

1 – To prepare for the lab, roll the modeling clay into a flat circle that fits inside the plastic plate. Make several

impressions of each tool in your slab of modeling clay.

2 – Use the ruler to record the measurements for each tool and its impression surfaces.

3 – Document any unique characteristics you notice on each tool or its impression. Write your observations on your

worksheet.

4 – After you have documents both of the tools at that station, roll the clay into another ball to prepare for the next group

and wait until it's time to rotate to the next station.


• Dimensions of the impression

• Ridges or striation patterns

• Defects, such as nicks and chips

• Paint chips or metal shards left on a tool

Type of Tool: ____________________

Tool # Width of Tip

(mm)

Length of Tip

(mm) Unique Characteristics (Defects, surface marks, etc.)

1

2

3

4

5

6


Type of Tool: ______________________

Tool # Width of Tip

(mm)

Length of Tip

(mm) Unique Characteristics (Defects, teeth, marks, etc.)

1

2

3

4

5

6

Tool Mark Challenge

A ______

B ______

C ______

D ______

E ______

F ______

G ______

# of

Guesses:

1

2

3

4

5

6

7

8

9

10

H ______

I ______

J ______

K ______

L ______


Bite Mark Impressions - Teacher Information

Materials: Small Styrofoam plates (1 per student)

Permanent Markers (1 per student)

Rulers (1 per student)

Assortment of soft candies (Swedish fish, orange slices, Laffy Taffy, circus peanuts, etc.)

Overhead Transparencies (Cut into fourths)

Timer

Directions:

Part 1: Make an Impression

Distribute Styrofoam plates and permanent markers to each

student Instruct students to bend the plate in half so that the top of

the plate is on the inside. They need to label one half with

"maxilla" and one half with "mandible".

Demonstrate how to make a bite mark impression on the plate.

Students will need to put the folded plate into their mouth as fall

as possible and bite down on it to make a good impression. They

should not bite too deep as to break through the plate.

Provide each student with a piece of clear transparency and a

permanent marker. They will need to place the plastic on top of

their impression on the plate and use a permanent marker to trace

the dental pattern onto the plastic as accurately as possible.

Have students unbend the plate and use a ruler to make the

required measurements for width and depth of the impressions on

both jaws. They will also need to note any unique characteristics

they observe, such as slanted teeth, spaces, evidence of braces,

etc.

Part 2: Tasty Testing

Pass out one piece of one type of soft candy to each student.

Instruct students to gently bite into each piece of candy in order to make an impression, but not

too hard to bite it in half.

Have the students record a rating for the quality of the impression (poor, fair, good) along with

their observations, such as candy sticking to their teeth or whether or not it was too hard/soft to

make a good impression.

Repeat the testing with the other types of soft candy available.

NOTE: Circus peanuts and Laffy Taffy seemed to work the best for our impressions.

Challenge (Optional)

To prepare for the challenge, provide each student with one circus

peanut. Have them bite into it (with the top of the candy facing into their

mouth) to leave an impression and label the top with MX for maxilla and

MN for mandible. Have students hand in their candy piece. Use a

permanent marker to write a number on the bottom of the candy. Use the


chart to keep a list of student names and numbers to check the challenge answers.

For the challenge, divide students into groups of 3-4 students. For each group, have them find all the

correct candy pieces using their Styrofoam plates and overlays. Keep track of the amount of time it

takes each group to complete the challenge.

Note: Be sure to have the groups search through all the candy pieces each time. Do not remove the ones

that have already been identified.

Challenge Key

Number Name Number Name

1

16

2

17

3

18

4

19

5

20

6

21

7

22

8

23

9

24

10

25

11

26

12

27

13

28

14

29

15

30


Bite Mark ID Name ___________________________

Part 1: Make an Impression

Follow the directions to create a bite mark impression. Use a ruler to make the

measurements needed to the nearest tenth of a centimeter and record your data in the

table below along with any notes regarding unique characteristics you observe in the

teeth.

Jaw Width Depth Unique Characteristics

Maxilla

Mandible

Part 2: Tasty Testing

Follow the directions and record your data below.

Type of

Candy

Quality

(Poor, fair, good) Observations

Part 3: Write a paragraph to summarize what you have learned about bite mark

impressions during this activity.

Idea submitted by Sandy Powell Worksheet by T. Trimpe 2007 http://sciencespot.net/

Tire TracksTire TracksTire TracksTire Tracks ChallengeChallengeChallengeChallenge Teacher Information

Materials Needed: 8-12 toy cars (Hot Wheels or Matchbox size work best, look for

distinct types of tires or use some tools to create your own

wear patterns on them)

Large white construction paper

Copies of Tire Tracks worksheet

Ink pads

Preparation:

1 – Label the cars with letters. As you create the original tracks in the next step, make a key for your records showing

which numbers on the Tire Tracks worksheet correspond to the letters on the cars.

2 - Roll the tires of each car on the ink pad and then roll across the Tire Tracks worksheet. Be sure to label the cars to help

you keep track of each set. If there is not enough space on the worksheet, make the tracks on another piece of paper and

cut/paste a good sample the best tracks into the boxes.

NOTE from T. Trimpe: A sample of my Tire Track Challenge is available on page 3 of this document.

3 - Make copies of the Tire Tracks Challenge worksheet (one per group.)

Activity Directions:

Day 1: 1 - Give each group a large sheet of construction paper along with rulers & paper towels.

NOTE from T. Trimpe: A PowerPoint to introduce the activity and challenge is available on the

Forensic Science page of my website in the Impression Evidence section.

2 - Give one car to each group and an ink pad. Allow time for each group to make a set of tracks on a plain white sheet of

paper. Have the groups pass around the cars so each group has a sample for each car. Save the sample tracks for the

challenge activity during the next class period.

NOTE from T. Trimpe: I set up 6 sets of cars (3 cars in each set) that can be passed around the room from

group to group. You might also consider setting up stations around your room. Place a few cars and one ink pad

at each station. Have the groups rotate through the stations to create their own tracks.

Day 2: 1 - Pass out copies of the Tire Tracks Challenge page and allow time for the students to identify the tracks and then check

their answers.

NOTE from T. Trimpe: I have several identification labs that are races – the first group done receives a prize

and bragging rights. I require the groups to have an answer for each item before they can check their

answers the first time. I mark the ones that are incorrect and the students keep working until they get them all

correct (or until at least half of the groups are finished.) To make it more challenging, provide more than 8

cars. The students will need to create tracks from all of the cars, but only some of them will be matches.

2 - Discuss how tire tracks can be used to solve crimes.

Extension Idea from T. Trimpe: Thanks to Chris Taylor, my favorite mechanic, I have a set of 10 actual tire

treads that I have the students use to make ink prints. They use black tempera paint (thinned with a little water)

and sponge brushes to coat the tread and make prints on pieces of white paper. I hang several "Mystery Tracks"

in my room that I made before class and see if the kids can match them to the real treads.

NOTE from T.Trimpe: I use the micropore ink

pads available from Quill – Item # 901-21281. The

ink pad is made from a harder material than the

standard foam pads and holds up well to repeated

use for this lab.


Group Members: ____________________________________________

Work with your investigative team to identify each set of tracks shown

below. Use the cars provided, ink pads, and white paper to make a set of

sample tracks. Compare your tracks with the ones shown below and

then write the letters in each box to show the matches.

#1 #2

#3 #4

#5 #6

#7 #8


Group Members: ___________________________________________

Work with your investigative team to identify each set of tracks shown

below. Use the cars provided, ink pads, and white paper to make a set of

sample tracks. Compare your tracks with the ones shown below and

then write the letters in each box to show the matches.

1. what is impression evidence? -...

Documents