File used in Forensic Science class on 9 and 13 January, 2017.

1. Dr. Sangeetha Balakrishnan
PG Department of Chemistry
Women’s Christian College
Chennai – 600 006
Fingerprints
Footprints
Tire Impressions
9 January, 2017
Forensic Science
PCH/NM/01

2. https://theabsentbox.wordpress.com/category/forensic-science/
Forensic Science LT 1: 18 January, 2017
Time: 1:45 to 3:15 pm
Assignment 1 Submission Date: 17 January, 2017

3. Classification of Fingerprints
Fingerprints
Loops Arches Whorls
Plain
arch
Tented
archType line
Loop Plain Arch

4. • Loop: friction ridge entering from one side of
the fingerprint, curving on itself, and exiting
the fingertip on the same side.
• All loops are surrounded by two diverging
ridges called type lines.
• Arch: ridges entering one side of the print,
rising to a peak, and exiting on the other side.
• Whorl: circular, oval or spiral
• Loops: 60-65%; Arches: ~ 5%, Whorls: 30-35%

5. Automated Fingerprint Identification
System (AFIS)
• A computerised database of digitised
fingerprints that are searchable through a
software.
• AFIS can store millions of print images of
fingerprints.
• This can be searched in minutes by a single
operator.
• This was developed by FBI and NIST.
• It is a 10-print system.

6. AFIS… cont’d
• Standard data format, but software and
computers that operate AFIS are not.
• Development: Integrated Automated Fingerprint
Identification System (IAFIS).
• IAFIS can:
– Enhance an image to improve its quality.
– Compare crime scene fingerprints against known 10-
print records retrieved from the database.
– Search the database for a single, latent print
developed from a crime scene.

7. AFIS
The identifying
characteristics
to look out for!

8. AFIS

9. Footwear Impressions
Footwear
Impressions
Sunken Surface
Also called 3D Impression Also called 2D Impression
Recipient object is soft or pliable: mud,
soft dirt, wet cement.
Recipient object is hard: granite/mosaic
floor.
Also called Positive Impression Also called Negative Impression
Transfer: shoe to surface Transfer: surface to shoe!
Negative impressions are less common. Why?

10. Footwear evidence is generally overlooked in crime scene
investigation!
– Footwear impressions are on the ground.
– They may not be clearly visible.
– They may have been trampled upon by paramedics and
other personnel at the scene.
A footwear impression can provide information on:
- Type and make of shoe.
- Size of shoe.
- Gait.

11. Food for thought.
a) When footwear impressions are obtained at the
scene of crime, are they known or unknown
evidence?
a) There are two pairs of shoes of the same type
and size. One pair is brand new. The other has
been used for a while. Classify impressions from
both pairs as Class or Individual Evidence.

12. What info do you get here?