Fingerprint and DNA Evidence in Forensic Investigations

Since the early 1900s, fingerprint evidence has been a cornerstone in crime scene investigations, helping to solve numerous cases. While fingerprints are considered unique, concerns have been raised about the accuracy of interpretation, particularly when left unintentionally at crime scenes.

In 1984, Professor Alec Jeffreys at the University of Leicester discovered key variations in DNA while analyzing X-ray films. This led to the development of DNA fingerprinting, which was commercialized in 1987. Today, it plays a crucial role in criminal investigations, paternity testing, victim identification, matching organ donors, and determining livestock pedigree. DNA evidence has even been used in high-profile cases, such as identifying Nazi doctor Josef Mengele in 1992.

Forensic laboratories typically use blood, semen, saliva, hair, or skin for DNA analysis, as all cells in the body share identical DNA. With only 0.1% of DNA being unique to individuals, the likelihood of two non-identical individuals having the same DNA fingerprint is one in 30 billion. DNA fingerprinting involves analyzing mini-satellites, which are repeated DNA sequences that do not contribute to gene function.

While DNA analysis is generally accepted in U.S. courts, issues surrounding accuracy, contamination, and privacy continue to raise ethical concerns. The Supreme Court ruled in 1985 that taking samples without consent does not violate privacy protections.

An example of DNA fingerprinting, in which ten different individuals are tested for six loci (locations of a DNA sequence on a chromosome).