“TRACE EVIDENCE ANALYSIS:THE FUTURE OF CRIME SCENE INVESTIGATION”

Name: Norashikin bt OthmanMatrix Nu. : SGC100014

MSc Analytical Chemistry and Instrumentation Analysis

SCGS6190/Seminar Presentation

CONTENTS1. Objectives2. Introduction3. Trace Evidence4. Importance of trace

evidence analysis5. Improved Techniques

and Technologyi. Glass Evidence Analysisii. Chemical Composition

Identificationiii. Collecting and analyzing

explosivesiv. Body Fluids and Fingerprints

Detection

6. Conclusion7. References

OBJECTIVES

To understand the evidential value of trace evidence in crime scene investigation.

To explore the new and improved techniques for detecting and distinguishing trace evidence.

To recognize the importance of modern analytical instrumentation in forensic science.

INTRODUCTION Forensic science is a scientific

approach and application of science to the requirements of law.

The scientific approach contributes to bringing the culprit to justice and exonerating the innocent suspect.

Forensic science investigations are based on Locard’s exchange principle and Principle of individuality.

INTRODUCTION

•In every contact between surfaces, there will be mutual exchange of matters across the contact boundary.

LOCARD’S EXCHANGE PRINCIPLE

•Identification or individualization is based on comparison.

•Two objects may be indistinguishable but not identical

PRINCIPLE OF

INDIVIDUALITY

Physical Evidence

Victims

Crime SceneSuspect

Victims, crime scene and suspect are all connected to one another through physical evidence. Finding of one of the element will bring the

discovery of another.

TRACE EVIDENCE Definition:

Trace evidence is minute quantities of natural and man-made materials

that readily transfer between objects or between people and objects.

TRACE EVIDENCE1. Hair 2. Fibers3. Paint4. Fingerprints5. Glass fragments6. Arson and explosives7. Gun shot residues (GSR)8. Narcotics and controlled

drugs9. Clandestine laboratory sample10.Biological sample - DNA11.Miscellaneous trace evidence

THE IMPORTANCE OF TRACE EVIDENCE ANALYSIS

Trace evidence provides connection between a person or object to a specific crime scene.

The connection is expected to conclude that two samples “could have” shared a common origin.

Conventional techniques are often unable to distinguish the unique characteristic of trace evidence for identification and comparison.

Forensic science investigation faces challenges in meeting the increasingly rigorous scientific standards and courts expectations.

Improved Techniques and Technology

Glass Evidence Analysis

Chemical Composition Identification

Explosives Collection and Analysis

Body Fluids and Fingerprints Detection

1) Glass Evidence Analysis Glass fragments are among the most frequently

encountered physical evidence at crime scene (Parker & Peterson, 1972).

Conventional methods rely on the comparison of glass physical properties between the known and questioned sample.

The difference of refractive indices and densities are utilized in forensic discrimination of glass samples (Buscaglia,1992).

Physical properties comparison offer discrimination but unable to provide classification of glass product type.

Improved glass manufacturing processes resulting in narrowing the range of refractive indices in modern glass.

1) Glass Evidence Analysis Quantitative elemental analysis enables

discrimination between known and question sample and classification of glass type of product use.

Three common techniques:i. Flameless Atomic Absorption Spectroscopy

(FAAS).ii. Inductively Coupled Plasma Atomic Emission

Spectrometry (ICP-AES).iii. Energy Dispersive X-Ray Fluorescence

Spectrometry (EDX-XRF)

Parameter FAAS ICP-AES EDX-XRF1.Destructive Yes Yes No

2.Level of detection Extremely sensitive Good Good (but varies with element, excitation, matrix)

3.Multi-element technique

No Yes Yes

4.Sample preparation

Intensive Intensive Virtually none

5.Automated Yes Yes Possible

6.Cost Moderate High Moderate (XRF), High (SEM/EDX)

7.Small sample size Extremely small Small to moderate SEM, very small

8.Speed of analysis Very slow Rapid Rapid

9.Precision Good High Good (but not at low concentration)

10.Accuracy High High Good

11. Availability in forensic laboratory

Possible Highly unlikely Possible

Table 1 Comparison of three common techniques for elemental analysis of forensic glass sample.

1) Glass Evidence Analysis

Highly discriminating techniques have been develop by International Forensic Research Institute – analyzing glass elements using inductively couple plasma-mass spectrometry (ICP-MS).

ICP-MS combines enhanced sensitivity and multi-element capability.

High level of glass analysis enable all types of glass to be distinguish. ICP-MS allows analysis of very small glass fragments.

2) Chemical Compositions Identification

Detection of chemical residues on clothing, fingernail, hair and skin samples are important to provide links between suspected sites and possible offender.

Conventional analysis attempts to break down the sample into separate chemicals.

This results in destroying the sample during the process.

Analysis of small sample size is often not precise enough for detection.

2) Chemical Compositions Identification

Static secondary ion mass spectrometry (SIMS) is used to distinguish trace chemicals on various materials.

SIMS identifies chemical composition of the surface of extremely small trace evidence sample – 1/10,000 of an inch.

Static SIMS show real potential as it able to differentiate and identifies specific samples of various physical evidence.

Colorants and chemicals on hair sample

Environmental contaminants

Illicit drug on synthetic fiber

Paint

Fingernail polish

SIMS SAMPLES DETECTION

3) Collecting and Analyzing Explosives Large bombing sites pose problems in collection

and identification of small quantities of explosive residue among large amounts of debris.

New method of blast debris collection utilize Teflon surface wipes.

Advantages of Teflon surface wipes:i. Shred resistantii. Dry sampling.iii. Applicable for various surfaces.

Evidence collected through dry surface wipes is transfer into gas chromatography column.

3) Collecting and Analyzing Explosives

The method are simple, inexpensive and can be readily adapted to forensic laboratory.

Portable gas chromatographs are commercially available.

Dry sampling should be adapted to crime scene of explosion since environmental factors may speed up sample decomposition.

4) Body Fluids and Fingerprints Detection

Conventional method for searching for bodily fluids and fingerprints is fluorescence method.

Fluorescence method has a drawback where the light emitted is weak compared to the surrounding room light or at the outdoor crime scene.

Criminalistics Light-Imaging Unit (CLU) is a multispectral imaging system.

CLU utilizes various colors of light to view the substances or structure being examined.

CLU allows detection under normal lighting conditions. This technique is five times more sensitive than

fluorescing method.

4) Body Fluids and Fingerprints Detection The usage of visible light in CLU allows location

and identification of blood evidence on dark surfaces.

CLU can detect untreated fingerprints on transparent, dark and multicolor surfaces.

CLU have camera’s video-recording features which work like a cam-coder.

CLU replacing the fluorescence method for detection of:Semen Stains

Blood spatter pattern and trails

Fingerprints

CONCLUSION

Advances in technologies for detection and distinguishing trace evident hold a great promise for speeding up evidence collection, limiting contamination and easing the analysis.

By generating stronger evidence, these more precise forensic tools will benefit every facet of law enforcement.

Justice vide forensic may be the order of the future crime scene investigation.

“THANK YOU”“Physical evidence cannot be wrong, it cannot

perjure itself, it cannot be wholly absent”-Professor Edmond Locard, -

REFERENCES ACP Dr. Yew Chong Hooi (2008). Application of Forensic

Science in Criminal Investigation: The way forward. Forensic Laboratory, RMP. Malaysia.

Supt. Shaikh Abdul Adzis (2006). Siasatan Forensik: Pengurusan Tempat Kejadian. Forensic Laboratory, RMP. Malaysia.

TA. Brettel, JM Butler & JR Almirall (2011). Forensic Science. Journal of Analytical Chemistry. ACS Publications.

NIJ Journal. (2003).Without a trace? Advances in Detecting Trace Evidence.

J.A Buscaglia (1992). Elemental Analysis of small glass fragments in forensic science. Criminal Justice, Science Department. USA.

B. Parker & J.Peterson (1972). Report of the National Institute of Law Enforcement and Criminal Justice, Washington DC. USA.