Examination of Firearms Review: 2007 to 2010 - Interpol

1. Abstract
This review focuses on the discovery, recovery, identification and individualization of
biological material important in forensic investigations. Several techniques will be
discussed that are currently applicable in the field of forensic biology. Furthermore
new techniques and developments that might become applicable to the field of
forensic biology in the near future will be discussed. The aim of this review is to give
a summary of new developments since Fourney et al 1 published a review in Interpol’s
Forensic Science Review (2007). The first chapter will deal with the discovery and
recovery of biological trace material at the crime scene. The second chapter
concerns individualization of the traces and focuses mainly on the biological
approach to identifying body fluids, where ribonucleic acid (RNA) will play an
increasingly prominent role. The last chapter deals with the individualization of crime
scene samples based on the deoxyribonucleic acid (DNA) content. The principal
topics this review covers are divided into: Trace evidence discovery and recovery;
Identification of blood, semen, and other body fluids; Individualization based on the
genetic fingerprint, epigenetic markers, short tandem repeats (STRs), single
nucleotide polymorphisms (SNPs), and present challenges (e.g. Quality Control).
Furthermore some techniques will be presented that could become valuable in future
forensic biological examinations. As in any review a selection had to be made on
many of the scientific topics papers that are relevant to the forensic scientist.
Therefore not all topics that are relevant to forensic biology have been dealt with.
Topics that relevant to forensic biology and are more than worth to be covered in
future reviews include Ancestry Informative Markers (AIMs), mtDNA analysis, and
nonhuman biological traces (e.g. microbial forensics).
2. Biological trace evidence
2.1 Introduction
Crime scene investigation is the first and a crucial step in forensic casework. The
time an investigating team can spend at a crime scene is limited due to
environmental factors, for example after a drive-by shooting a road must be screened
for evidence as soon as possible so it can be re-opened for the public in order to
prevent a chaos. After the road is re-opened any remaining traces will be destroyed,
thus an investigating team has only one opportunity to collect the evidence. It is
therefore essential that techniques are being developed that can give immediate
results to aid the investigating team on how they should proceed. Such techniques
should for example aim at the detection and identification of biological traces.
2.2 Biological traces
Presumably when we think of biological traces found at a crime scene, blood comes
to mind first. Besides blood, there are many more biological traces that are
interesting for forensic examinations (e.g. skin cells, semen, and hairs). This review
focuses on the identification of five different body fluids being: blood, semen, saliva,
vaginal fluid, and urine. Because body fluids all serve a different function and can be
323