Forensic DNA fingerprinting involves the collection and examination of biological evidence for purposes of identification. Using the unique DNA composition found in materials such as blood, hair follicles, skin tissue, bone and semen, scientists can generate a profile, or “fingerprint,” of each individual. Ongoing advancements in DNA fingerprinting technology have led to shocking criminal discoveries and helped researchers to gain insight into human history.
Criminal cases lacking sufficient evidence to convict a suspect are often closed after a period of years, leaving the families of victims without closure or justice. A DNA database containing blood samples from criminal offenders has been established, allowing law enforcement teams to search for DNA matches when materials are collected from a crime scene. Since past offenders are likely to commit other crimes in the future, the new sample entered into the system may match preserved evidence from cold cases. For example, in 2001 a suspected rapist/murder was arrested more than 10 years after his initial crimes. The “Night Stalker” case was solved when old evidence taken from vaginal swabs was matched with a recent DNA sample from the database.
The Innocence Project reported that the availability of DNA evidence has led to 249 postconviction exonerations between 1989 and 2009. Among the exonerated, 150 were African American, many of whom were convicted due to eyewitness misidentifications by individuals of another race. Other causes of wrongful convictions have included flaws in the justice system, such as false confessions brought on by coercion and testimony deals made with key witnesses.
Blood and tissue samples are commonly used to determine a parental relationship, as well as other familial connections. These techniques are especially useful when an infant is switched at birth or an adopted child needs information regarding family medical history. According to the DNA Initiative, paternity testing is regularly performed in over 150 forensics labs across the country.
DNA analysis is an important aspect of identifying missing persons and victims of events that cause mass fatalities, such as Hurricane Katrina and the World Trade Center attacks. The effectiveness of DNA analysis is challenged by severe deterioration or fragmentation of the remains, but scientists are often able to extract a sufficient sample to compare to the deceased individual’s medical records or the DNA of close relatives. While contested by some forensic researchers, historical cases of body identification have included the remains of Czar Nicholas and the Romanov family.
The study of similarities in DNA structures and gene traits has helped scientists to re-examine various aspects of human history, including migrational patterns that could potentially test modern beliefs about race and genealogy. Based on the evaluation of factors like chromosomal patterns, scientists have found that ethnic groups who are geographically separated and normally considered to be unrelated may share genealogical lines. Establishing these connections opens the door to painting a clearer of picture of migration and interaction in the past.