Since the first use of DNA evidence in a criminal case in 1986, forensic scientists have considered biological material (such as hair, skin, and bodily fluids) to be relatively reliable physical evidence.
While early technology required a substantial amount of biological material to extract enough DNA to build an individual profile for analysis, researchers have since discovered that they can obtain reliable DNA from more than just bloodstains or visible fluids; they can also obtain it from “touch DNA” that is left behind on surfaces or objects such as doorknobs, window latches, or steering wheels. Although touch DNA can be essential for forensic casework, it also comes with its share of issues, including those related to:
- Low quantity of useable DNA.
- High variability in the amount of DNA left by touch; that is, high variability in the amount that one person leaves, and high variability in the amount left from person to person.
- DNA degradation,including the many factors that can cause DNA to break down over time.
Continue reading “Persistence of Touch DNA Evidence for Analysis”