Dr. Sangeetha BalakrishnanPG Department of Chemistry

Women’s Christian CollegeChennai – 600 006

FingerprintsFootprints

Tire Impressions

9 January, 2017

Forensic Science PCH/NM/01

https://theabsentbox.wordpress.com/category/forensic-science/

Forensic Science LT 1: 18 January, 2017Time: 1:45 to 3:15 pm

Assignment 1 Submission Date: 17 January, 2017

Classification of FingerprintsFingerprints

Loops Arches Whorls

Plainarch

TentedarchType line

Loop Plain Arch

• 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%

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.

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.

AFIS

The identifying characteristicsto look out for!

AFIS

Footwear ImpressionsFootwear 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?

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.

Food for thought.

a) When footwear impressions are obtained at the scene of crime, are they known or unknown evidence?

b) 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.

What info do you get here?