A Brief History of DNA Evidence

January 1, 2022 | By Shane Phelps Law
A Brief History of DNA Evidence

DNA evidence has played a significant role in criminal investigations for nearly four decades. Many convicted felons have been exonerated because of DNA evidence and others have been caught for crimes that occurred before the advent of this technology. We are taking a look at the history of DNA technology, it is role in criminal investigations, and it is potential for criminal justice reform.

What Is DNA?

To understand DNA evidence, it is important to understand DNADeoxyribonucleic acid or DNA is a foundational material that records genetic information. Hereditary traits like blue eyes or curly hair are passed down through DNA to the next generation. This genetic information is present in the nucleus of a person’s cells and acts as a blueprint for human development.

DNA is a double helix molecule formed by base pairs attached to a sugar-phosphate spiral. This structure is similar to a spiral staircase with the railings made of sugar-phosphate and the stairs composed of combinations of adenine, thymine, guanine, and cytosine. DNA can replicate itself and the potential replication is based on the specific sequence of bases within the helix. DNA can be found in skin tissue, hair, blood, saliva, and other parts of the human body.

Through DNA, researchers can discover root causes of genetic diseases, predict traits, and decode life itself. The majority of DNA research came as the result of an increased interest in the human genome. Genes were the term scientists used in the 20th century to describe the smallest unit of genetic information. While researchers understood the theory of genetics, genes were unknown; there was no information about where they were stored or what they looked like chemically and structurally.

Finally, thanks to the groundbreaking research from chemist and x-ray crystallographer Rosalind Elsie Franklin and geneticists Francis Crick and James Watson, DNA was discovered. Later, scientists would find a practical use for DNA in criminal justice.

The First Use of DNA in a Criminal Case

In the 1980s, British genetics professor Alec Jeffreys discovered patterns within DNA that distinguished one person from another. He developed a DNA recognition technique that he used to determine paternity and provide evidence in immigration cases.

Then, in 1986, British police asked Jeffreys to use DNA recognition to confirm a suspect in a murder case. Police had a suspect, Richard Buckland, who confessed to the murder, but investigators wanted to use modern technology to prove, without a shadow of a doubt, that Buckland was the murderer or not. Prof. Jeffreys compared DNA samples from the crime scenes and found that the DNA did not match.

The police had no choice but to collect DNA samples from those living in the area who fit the general description of the murderer. Over 4,000 samples were collected but there were no matches. Later, police discovered that one man was paying people to provide DNA samples on his behalf. Police found and arrested Colin Pitchfork whose DNA matched the crime scene samples. He was convicted to life in prison the next year.

DNA in the Modern Age

Now, DNA is still a cornerstone of most investigations, but it cannot be the only evidence of wrongdoing. Convictions must be compelling and based on more than one piece of evidence. Criminal cases over the last 40 years have made it apparent that DNA at the scene of the crime does not always mean that a person is guilty. In some cases, DNA from family members, visitors, or other people may be present at the scene.

Investigators have also found that DNA has a shorter shelf life than other types of evidence. DNA is biological material which means it is capable of decay. Hair, blood, and other samples break down over time and storing it incorrectly could cause irreparable damage.

The O.J. Simpson trial is a prime example of the need for proper procedure. In this case, there were no witnesses to the murders of Nicole Brown Simpson or Ron Goldman, so DNA evidence was a significant part of the prosecution’s case against O.J. Simpson. There were over 100 exhibits of DNA evidence presented at the trial.

However, the most compelling evidence was mishandled and contaminated during the period between Simpson’s arrest trial. Because the prosecution’s case relied heavily on the DNA evidence alone, their argument quickly lost credibility when it became evident that police mishandled the evidence.

Criminal Justice Reform

In recent years, DNA has been used to exonerate death row inmates who have been wrongly accused. The Innocence Project and other organizations are working to tirelessly to provide inmates with a second chance. The process is slow but sure and each year more inmates are set free. The future of DNA evidence is bright, but there is still work to be done to research genetics.

If you have been accused of a crime, contact Shane Phelps Law.