Fingerprints, Footprint Impressions, and Tire Impressions

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Transcript of Fingerprints, Footprint Impressions, and Tire Impressions

Fingerprints Footprints Tire Impressions

Dr. Sangeetha BalakrishnanPG Department of ChemistryWomens Christian CollegeChennai 600 006FingerprintsFootprintsTire Impressions9 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 Fingerprints

PlainarchTentedarchType lineLoopPlain 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 spiralLoops: 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 contdStandard 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.

AFISThe identifying characteristicsto look out for!

AFIS

Footwear ImpressionsAlso called 3D ImpressionAlso called 2D Impression

Recipient object is soft or pliable: mud, soft dirt, wet cement.Recipient object is hard: granite/mosaic floor.

Also called Positive ImpressionAlso called Negative Impression

Transfer: shoe to surfaceTransfer: 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.When footwear impressions are obtained at the scene of crime, are they known or unknown evidence?

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.

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