Crime screen examination
FORENSIC SCIENCE INTRODUCTION

1 What is Forensic Science?

What is the relationship between forensic science and the law? A general definition is that forensic science involves ‘the use of science in the investigation of crime by the police and by the courts as evidence in resolving an issue in any subsequent trial.’’
The point of forensic science is to generate forensic evidence , that is, to establish a material fact in issue. So, if it is clear on the evidence that a death was intentional and the issue before the jury to decide is whether or not the accused caused the death, then the forensic link via DNA or fingerprint between the accused and a murder weapon will go towards establishing that fact in issue.

Kiely says that forensic evidence comes to the law in either or both of two forms. The first is as a class characteristic statement, for example: that the hair fibre found comes from a human or an animal or perhaps from a Caucasian or and Asian male, or the approximate age of the body whose bones have been located. The second is a more specific individual statement that forensically links suspect A to the crime scene, for example hair fibres consistent with the suspect that have been found at the crime scene.

The term forensic evidence contains two concepts. The term forensic refers to the process by which facts are generated, that is, the mechanism by which fingerprints are obtained and matched while the evidence aspect refers to the process of using the forensic ‘facts’ in litigation.

2 The Crime Scene

The crime scene may consist of more than just the location in which the crime occurred. Four possible crime scenes are:

1. The actual crime scene, which may be, for example a body stabbed to death, and the knife left by the side of the body.
2. The crime scene material that is collected at the scene: for example where the perpetrator or accused has left the murder weapon, and possibly his bloody fingerprints at the crime scene as well as possible fibres from his clothing.
3. The crime scene material that can be tested and the results of any tests; for example where in the example given above, bloody fingerprints are so smeared that no print can be clearly detected or perhaps the crime scene has been contaminated in some way rendering some evidence virtually un-testable
4. The crime scene information that is eventually admitted into evidence subject to the particular case and the rules of evidence applicable. Even if the materials found are capable of being tested and yield results, the point of the exercise is to forensically link the suspect with the crime scene and therefore the victim. To establish that link, the prosecution must call expert scientific evidence as to the particular methods used to match or make comparisons, the reliability of the methods used and the eventual results and the likelihood of the link between the particular material analysed and the suspect. The giving of the information of the test results amounts to factual information – the likelihood of the forensic link will amount to opinion evidence based on what the expert knows of the particular field, and expert opinion evidence must meet certain criteria in order to be admissible.
Each stage or crime scene therefore will be critical. The persons who examine the crime scene must be able to recognise what is present at the scene that may be relevant to the crime and those who collect the evidence need to ensure that the evidence is collected without risk of contamination or destruction. Optimally, the forensic laboratories will be equipped with competent staff and current testing procedures while the experts who will give evidence based on the analysis of crime scene evidence must satisfy the rules of evidence.

Each stage, however, will be susceptible to scrutiny from defence lawyers. The police case, may to a great extent, depend on the care taken at the first three stages. While they may have some control over the first two stages, police rely on the competency of personnel and procedures at the third stages.

This places increasing pressure on lawyers to develop even a basic understanding of the scientific principles involved so as to be able to competently cross examine on a particular area.
3 Forensic Science in the Court Room: the Judge and Jury

Readings

Wheate, Rhonda M. ‘Australian Juries And Scientific Evidence’ . Australian Journal of Forensic Sciences, v.38, no.2, July-Dec 2006: (75)-84.
(Available through the RMIT Library – Informit Database)

Wood, James. Forensic sciences from the judicial perspective [Presented as a Plenary Lecture at the ANZFSS International Symposium on the Forensic Sciences (16th: 2002).] Australian Journal of Forensic Sciences, v.35, no.1, Jan-July 2003: (115)-132.
(Available through the RMIT Library – Informit Database)