Biology Reference
In-Depth Information
Samples recovered from
scenes of crime
Forensic
biologist
Reference
samples
from suspects
Reference
samples
from victims
Forensic geneticist
Report/intelligence
Figure 1.1
The role of the forensic geneticist is to assess whether samples recovered from a crime
scene match to a suspect. Reference samples are provided from suspects and also victims of crime
scenes with suspects and possibly victims, resulting in a report that can be presented
in court or intelligence that may inform an investigation (Figure 1.1).
Several stages are involved in the analysis of genetic evidence (Figure 1.2) and
each of these is covered in detail in the following chapters. In some organizations
one person will be responsible for collecting the evidence, the biological and genetic
analysis of samples and ultimately presenting the results to a court of law. However,
the trend in many larger organizations is for individuals to be responsible for only
a very specific task within the process, such as the extraction of DNA from the
evidential material or the analysis and interpretation of DNA profiles that have been
generated by other scientists, or just reporting the findings.
A brief history of forensic genetics
In 1900 Karl Landsteiner described the ABO blood grouping system and observed
that individuals could be placed into different groups based on their blood type. This
was the first step in the development of forensic haemogenetics. Following on from
this, numerous blood group markers and soluble blood serum protein markers were
characterized and could be analysed in combination to produce highly discriminatory
profiles. The serological techniques were a powerful tool but were limited in many
forensic cases by the amount of biological material that was required to provide
highly discriminating results. Proteins are also prone to degradation on exposure to
the environment.
In the 1960s and 1970s, developments in molecular biology, including restriction
enzymes, Sanger sequencing [68] and Southern blotting [69], enabled scientists to
examine DNA sequences. By 1978, DNA polymorphisms could be detected using
