2 DNA: Forensic Scientist
Forensic scientists specialise in different areas, using scientific methods to analyse traces recovered from crime scenes and items recovered from victims and suspects. They interpret the data produced from their analysis and evaluate their findings within the context of the specific case.
In this case, a Forensic Biologist (DNA), Fingerprint Expert and a Digital Forensic Expert would likely be involved. We will go through the DNA and digital expert roles.
Forensic Biologists examine biological traces like blood, other body fluids, hair, and DNA swabs. They receive traces recovered from the crime scene, and they document these items in detail, often including diagrams and photographs. They may conduct tests, typically by swabbing to see whether a body fluid is present on the item and then collect a sample of it. If a DNA profile is needed from the collected samples, a number of lab processes are carried out:
- DNA is extracted from the cells.
- Copies of the DNA are made through a process called Polymerase Chain Reaction (PCR).
- DNA fragments are separated and visualised to produce a DNA profile.
- A DNA profile from a crime scene can then be compared to the profile of a victim or suspect to see if they are the same or different.
- Unknown DNA profiles may be loaded onto the National DNA Database to search for matches.
- Results of such analyses can be provided in a statement and presented in court. This is done by a likelihood ratio which will be discussed in Week 3.