Thanks to television detectives, the power of forensic DNA evidence is well known. Viewers are familiar with criminals leaving their DNA at the scene of a crime – allowing police to identify perpetrators with a high degree of accuracy, as well as any other crimes they may have committed.
Even if there is no arrest before the end credits, the crime scene DNA will be stored on a database, and later used to find a “matching” suspect.
In real life, this practice has been used successfully in widely reported court cases. Serial rapist Keith Samuels was caught after a 14-year hunt and a DNA test, while triple murderer Joseph Kappen was identified after his death when a DNA match was found with his exhumed remains.
The successful use of DNA in cases such as these, solving apparently unsolvable crimes, has led to significant public investment and political commitment to expanding forensic DNA databases. But the limitations of DNA evidence, and just how carefully it must be handled (by police officers, scientists, lawyers and juries) is rarely mentioned.
Recent research highlighted eight cases that were overturned in the last six years due to concerns over the DNA evidence.
Although the research indicates that there is a smaller risk of DNA being misleading than other evidence types, there needs to be clarification over issues such as DNA contamination, the interpretation of partial or mixed profiles, trace analysis and the transfer of DNA. When DNA science pushes boundaries, extreme care is required to avoid miscarriages of justice… Read more
By: Carole McCartney and Aaron Opoku Amankwaa
Source: The Conversation