CHAPTER 3: Use of Light in the Detection of Genetic Variation of Forensic Importance

The discovery that people have unique DNA profiles and its subsequent use in criminal casework has revolutionised the field of forensic science. It can be argued that no other single approach since that of traditional ink-based fingerprinting has done more or can provide greater evidence to link a suspect to a crime scene. In addition to individual identification, there are a myriad of other genetic tools used to identify specific gene markers allowing identification of body fluids at crime scenes, phenotypic trait inference of suspects or identification of endangered species illegally traded. While each approach used may vary in complexity, marker type, platform, data interpretation, and application, the overriding common element used in all these approaches is their use of PCR based amplification techniques and fluorescent dyes and fluorophores used to detect DNA sequence differences. In this Chapter the current processes used in the forensic analysis of DNA and RNA are covered detailing why light is essential for detection but also destructive to the template DNA collected during a criminal investigation.