This document discusses different types of impression evidence, including patent impressions, latent impressions, and plastic impressions. It also covers shoe impressions, tire tread impressions, and dental patterns. Shoe impressions can provide information about a person's size, weight, activities, and gait. Tire tread impressions can indicate the make and model of a vehicle. Dental patterns can be used to identify remains or link a bite mark to a suspect. The case of Ted Bundy is discussed as an example where dental impressions from a bite mark left on a victim were used to identify and convict Bundy.

1. DRYSDALE CSI
Casts and impressions.
Ian Anderson
Saint Ignatius College Geelong

2. TYPES OF IMPRESSIONS.
 Three basic categories:
 Patent impressions.
 Latent impressions.
 Plastic impressions.
Source: Bertino & Bertino, 2012

3. TYPES OF IMPRESSIONS.
 Patent impressions.
 Two-dimensional impressions.
 Visible.
 Produced when material (such
as soil, dust, paint, blood, etc.) is
transferred from an object (e.g.
the sole of a shoe, tread of a
tyre, etc.) and deposited onto a
hard flat surface.
Source: Bertino & Bertino, 2012

4. TYPES OF IMPRESSIONS.
 Latent impressions.
 Two-dimensional impressions.
 Invisible to the naked eye, but
can be made visible by dusting
and electrostatic techniques or
chemicals.
 Produced when minute debris
(such as oil, fine soil, etc.) is
transferred from an object (the
sole of a shoe) and deposited
onto a clean floor.
Source: Bertino & Bertino, 2012

5. TYPES OF IMPRESSIONS.
 Plastic impressions.
 Three-dimensional imprints.
 Visible.
 Produced when an object (e.g.
the sole of a shoe, tread of a
tyre, etc.) is pressed into
soft, plastic material such as
mud, sand or snow.
Source: Bertino & Bertino, 2012

6. IMPRESSIONS.
Are impressions individual or class evidence?
 Depending on how they are made, impression
evidence can be classed as either individual or
class evidence.
 Class evidence:
 Tread pattern of shoes or tyres may
identify a brand and size, but it will
not identify a specific person or tyre.
Source: http://www.criminaljusticeschoolinfo.com/impression-
evidence.html

7. IMPRESSIONS.
Are impressions individual or class evidence?
 Depending on how they are made, impression
evidence can be classed as either individual or
class evidence.
 Individual evidence:
 Distinguishing
characteristics on the
impression, such as
defects or unusual
wear, can be used to
identify a specific
person or tyre.
Source: http://www.fbi.gov/about-us/lab/forensic-science-
communications/fsc/july2009/review/2009_07_review02.htm

8. SHOE IMPRESSIONS.
 Much information can be obtained from a shoe
impression, including:
 Size of shoe imprint  size of a person’s foot.
 Depth of shoe or foot imprint  person’s weight.
 Type of shoe (e.g. work boot v flat dress shoe)  information
on the person’s job or personality.
 Brand of shoe  information about the buyer.
Source: http://thestylesketcher.blogspot.com.au/2011/04/back-to-
drawing-board.html

9. SHOE IMPRESSIONS.
 Shoe wear patterns.
 Wear patterns on a shoe are
different from person to person.
 Even on the same type of shoe!
 Factors that personalize a shoe
pattern includes:
 Body weight.
 Shape of the foot.
 Whether the person walks with
their toes pointing straight ahead or
pointing in or out.
 The wearer’s activities.
Source: Bertino & Bertino, 2012

10. SHOE IMPRESSIONS.
 Gait and tracks.
 A person’s walking habits (gait) can be determined by
examining numerous prints together.
 e.g. A limp will result in an asymmetrical gait.
 The tracks can indicate whether a person is walking or
running.
 Based on length of stride and the pressure and shape of the
impression.
Source:
http://www.forensicsreport.com/research/A_formula_that_can_calcul
ate_a_persons_speed_by_just_looking_at_their_footprints.asp

11. COLLECTION OF SHOE IMPRESSION EVIDENCE.
1. Photograph impressions.
Source: Bertino & Bertino, 2012

12. COLLECTION OF SHOE IMPRESSION EVIDENCE.
1. Photograph impressions.
2. Lifting latent impressions.
 Using a range of methods including:
 Luminol – for bloody footprints.
 Dusting.
 Electrostatic lifting.
Source: Bertino & Bertino, 2012

13. COLLECTION OF SHOE IMPRESSION EVIDENCE.
1. Photograph impressions.
2. Lifting latent impressions.
 Using a range of methods including:
 Luminol – for bloody footprints.
 Dusting.
 Electrostatic lifting.
3. Casting plastic impressions.
 A cast can be made of a three-dimensional shoeprint.
 Exact method depends on conditions at the crime
scence.
 e.g. on sand:
 Hair spray is sprayed onto impression.
 Plaster of Paris is poured into impression.

14. COMPARISON OF SHOE SIZE V HEIGHT.
 A person’s height is usually related to a their shoe
size.
 The shoe model must first be identified before the shoe
size of an impression can be determined.
 A running shoe Size 9 will be shorter in length than a work
shoe Size 9.
Source: http://cantorsappsychologyblog.blogspot.com.au/2011/09/blog-comment-3-
correlation-project-hair.html

15. TYRE TREADS AND IMPRESSIONS.
 Tyre marks may indicate the speed a car travelled
when it skidded off the road, or the direction it
travelled as it accelerated from the crime scene.
 Motor vehicles can leave patent, latent or plastic
tyre patterns.
Source: http://www.dailymail.co.uk/news/article-2247011/Jerry-Brown-alive-
shouting-help-accident-drunk-Josh-Brent-did-witnesses-claim.html

16. TYRE TREADS AND IMPRESSIONS.
 Tyre tread and impressions are examined for two
characteristics at a crime scene:
 Tread pattern & measurements.
 To identify the type of tyre and perhaps make & model of the
car.
 Tyre tread impressions  tyre brand.
 Track width, wheel base & turning
circle  make & model of car.
 Nature of the impression.
 To determine how the vehicle was
driven.
Source: http://www.resolvematters.ca/index.php?pid=7&ref=1037

17. DENTAL PATTERNS IN FORENSICS.
The individual pattern of teeth can be used in two
ways.
1. Dental remains can be used to identify an
individual.
 Teeth are compared against available dental records.
2. Bite patterns can be used to identify a suspect.
 Reliability depends on the number of points of
comparison and
the clarity of the
impression.
Source: Bertino & Bertino, 2012

18. CASE STUDY.
Ted Bundy (1978).
A man wearing a stocking cap
entered a Florida State
University sorority house and
attacked some of the women
inside. Two women were killed
and two more seriously injured.
One of the women had a bite
mark that was photographed as
evidence. Subsequent attacks
followed in other states.
Source:
http://www.telegraph.co.uk/news/worldnews/northameric
a/usa/8678555/Blood-of-serial-killer-Ted-Bundy-
discovered-by-police.html

19. CASE STUDY.
Ted Bundy was charged with the Florida
State University attacks after his dental
impressions were compared to those
left on a victim.
The FBI’s Behavioral Science Unit had
profiled Bundy as a very
neat, organized, serial killer. Bundy was
so meticulous that he never left
fingerprints even in his own apartment.
Bundy escaped from police twice, only
to be recaptured. Bundy was found
guilty of murder and was executed in
1989. Before his execution, he implied
having committed approximately 50
murders!
Source:
http://anilaggrawal.com/ij/vol_005_no_002/reviews/tb/pa
ge008ex.html

20. http://sick9CSI.wikispaces.com/