In 1989, a young man, Gary Dotson, left prison after being unjustly convicted and spending six years in jail because someone convicted him of a crime he never committed. Not through a clever lawyer, not a law secreted witness, but his innocence was proved by blood, rather than a drop of blood. The appeal of the rape conviction of Dotson was based on circumstantial evidence relying on a testimony that was later changed, and at the same time lacked any feasible defense. However, the revolutionary application of DNA testing, which at that point was a young technology, was later used to prove that he was innocent.
This case scene of forensic science and justice is turned upside down. It was one of the first practical pieces of evidence in the world of blood, a silent and dead object that could speak more eloquently than any criminal court could [1].
In the modern world, DNA and serology are transforming criminal justice systems of the world, offering a combination of clarity and confusion in equal portions [2]. This article is about to discuss how such powerful tools are changing the way investigations are being carried out, righting historical wrongs, and drawing new issues of ethical concern, a bridge between the forensic science world, which can be daunting to the lay person, and the masses.
Bloodstains to Breakthroughs: A History of DNA and Serology Sciences
Evidence tells a story at the part of every crime scene. It is sometimes the hair left behind, sometimes the saliva on the tongue, or more usually, blood. In that, blood is the code to define us, DNA.
About every cell in our bodies has an outstanding DNA genetic blueprint. The DNA profile of two individuals (except identical twins, even though they have small genetic differences and don’t have the same DNA) is never the same. This is what makes it an extremely powerful tool of identification.
DNA is isolated from biological substances that are present, such as the use of blood, semen, saliva, and even skin cells, and this is what is compared with the DNA-sample of a suspect with Short Tandem Repeat (STR) analysis. STRs are small, repeated items of DNA that have large differences among individuals, and they code like a genetic barcode.
Serology was the gold standard before the entry of DNA into the forensic spotlight in the late 1980s. Serology denotes the examination of body fluids (blood type, such as A, B, AB, O) and screenings of protein and enzymes, and the material of such fluids as semen or saliva. Serology is not the ultimate answer like DNA, but it can provide context, e.g., it can distinguish whether blood was human or it can identify body fluids at a scene.
These two components, DNA and serology, create a powerful duo. One determines the who; the other usually describes the how and what [3].
How has DNA Evidence Transformed the Landscape of the Law
Before the popularity of DNA testing, criminal investigations would usually attempt to build a case using circumstantial evidence, eyewitness accounts, or confessions, many of which were fabricated, unreliable, or inaccurate. The courts lacked a foolproof method of proving the innocence or guilt of a person. This led to thousands of innocent people being sent to prison and, in other unfortunate instances, to the hangman.
This was revolutionized by DNA profiling. Closely preceding was Colin Pitchfork of the UK in 1987, who was the first convicted murderer using DNA evidence and the first to have the evidence overturned during the investigation. His conviction put an end to a series of unexplained killings, and the floodgates of forensics breakthroughs were opened.
In the U.S., the Innocence Project has succeeded in clearing more than 300 individuals through DNA tests, some of them being on death row. Those are not mere figures; those are lives that DNA saved [4].
The testing of DNA has changed the balance in courtrooms. It not only works with arguments that are persuasive, but also works with data, probabilities, and profiles. DNA match is even more powerful than an eyewitness or even a confession. However, with great power comes great responsibility, and the law system still had to change, and there it was ensured that the DNA evidence was harvested, stored, and interpreted to the best of its knowledge.
What about the Drop of Blood that goes into the Court?
Although forensic science might appear to be a complicated field of study, it is conducted in a very systematic way. Let us take a step through the way one drop of blood at a crime scene can turn out to be powerful evidence in the court of law. Every step is important, since the integrity of the evidence lies in it.
Step 1: Taking control of the Crime Scene
The initial step of testing should be securing the crime scene before any tests are done. A perimeter is set up by the police and the forensic investigating teams to make sure no one tampered with or contaminated evidence; this is referred to as preservation of the scene. They cover themselves in gloves, masks, and even suits at times to make sure they do not leave their carrier’s DNA and disturb any remaining evidence. Photos, drawings, and notes are collected in order to fix everything as it was discovered.
Step 2: Locating and Gathering Blood Evidence
Forensic specialists search visible blood pools, smears, or droplets. However, not every blood is evident. It is sometimes cleaned up or covered up. Special tools are where it comes in. They could use what is known as luminol, which is a chemical that reacts with hemoglobin in blood and produces a dark-glowing reaction. Samples are then identified and carefully collected by using clean, sterile swabs, cloth, or scalpel blades on dry stains.
The sample is put into a clean, labeled container, usually a paper envelope (not in a plastic container, which collects moisture, leading to mold). Labels contain the date, time, place, and the person identifying them (initials). This is the origination point of the chain of custody, a document with all details of who performed discovery of the evidence at each point.
Step 3: Sample Preservation and Transportation
Blood evidence is sensitive. It is to be dried in full before being packed in order to avoid degradation. Wet specimens are kept at low temperatures and rushed to a forensic laboratory. Delivery is not something that can be done by simply placing biological evidence in the bag; the couriers have specific regulations, and they observe temperature and even security. This ensures the integrity of the evidence; therefore, it stands up in court.
Step 4: Initial Serology Analysis
After arriving at the lab, the initial tests are usually serological. These tell us whether the substance is even blood (it may be paint, dust, or another substance). In case that it is established to be blood, there are other subsequent tests that scientists can perform to ascertain that the blood is human or animal blood, and in addition, it may have other bodily fluids in it, i.e., saliva or semen.
Blood type (A, B, AB, or O), or Rh positive or negative, can be read serologically, as well. Although not as distinctive as DNA, blood typing withers assists in the identification of the suspects, particularly where DNA is too deteriorated to be examined.
Step 5: Extracting and amplifying DNA
When the DNA test is possible, scientists start by extracting DNA from the cells of the blood. This is based on breaking open the cells as well as isolating the DNA. However, there is only a small fraction of this most of the time, so what they do is boost it up through the procedure known as PCR (Polymerase Chain Reaction).
PCR replicates a million copies of the DNA to get sufficient material to research. As little as a trace of blood may give a complete DNA profile, as long as the sample is not severely degraded or contaminated.
Step 6: DNA Profiling and Comparison
Upon amplification, forensic scientists examine certain parts of that DNA called Short Tandem Repeats (STRs) [5]. They are repetitive DNA sequences that differ among individuals each other- some kind of a biological fingerprint.
One ends up with a distinctive profile, a series of numbers that signify the repeats. A comparison is then made with known samples. These could be of a DNA database such as CODIS (in the U.S.) or of the national directories in the other countries, a suspect, or a victim. A match may testify heavily against a person-or eliminate him.
The determination of a DNA test is commonly given with a rate of certainty of the statistical outcome. An example would be when scientists would argue that the possibility of another individual with such DNA type is 1 in 3 billion. This is how powerful the evidence may be.
Step 7: Bloodstain Pattern Analysis (BPA)
Other than identification, the story can also be told through blood alone. Bloodstain Pattern Analysts, professionals, examine the droplet shape, movement, and location. Was it a spatter or a smear? Was it a splash of blood that is high impact, or a drip of blood because of a wound?
BPA can indicate whether a victim was standing, sitting, or moving. It may also assist in identifying the chronological order of what happened, i.e,. Who initiated the attack, and where and how the attack commenced, as well as whether the scene is staged.
It is like putting together a crime in the language of physics, where blood is the ink, and where gravity, motion, and force are the grammar [6].
Step 8: Proper presentation of Evidence to the Court
After analysis has finished, the forensic experts compile thorough reports and, in many cases, even draw illustrations, such as graphs of DNA profiles or maps of bloodstain patterns. They are supplied to the legal team and can form some of the evidence provided in court.
The forensic scientist who runs the tests can be issued as an expert witness. It is not their responsibility to demonstrate that someone is guilty or not guilty, but to tell what the evidence demonstrates in terms that are clear and non-technical, which can be understood by a jury.
Questions will be put to them on their methods, the way the evidence was treated, and possible contamination or error. The soundness and the documentation of the forensic procedure validate the whole investigation.
Step 9: Constructed Evidence Interpretation
Lastly, one is supposed to keep in mind that DNA or serology does not operate alone. Blood evidence should be considered in the context of other case facts: eyewitness accounts, alibis, motive, opportunity, and material evidence such as fingerprints or weapons.
For example, when the blood of a suspect is detected on the spot, the context is important. Were the residents there? Was there any need for them to be there? Did the blood left at the crime deposited at the crime scene, or before the crime? That is why it is not only lab results, but also expert interpretation used in courts. Forensics helps to rule out some of the probabilities, but it requires good thought to draw a legal inference.
Hence, when the blood is found at a crime scene to its eventual presentation in a courtroom, it has undergone an amazing journey. It transforms a stain on the floor into a biological storyteller of events in that it tells us who or what was present, what took place, and on some occasions, even the cause. Forensic science, as far as the general populace is concerned. It does not consist of magic. It is not a TV soap. It is a cautious, scientific procedure-established on skillfulness, forbearance, on reality.
Since in the justice world, blood does not lie.
Ethical Issues and the Science: Could We Believe the Science
Despite its power, DNA is not all that infallible.
The samples are susceptible to contamination, degradation, or mixing. Multiple touches may deposit or leave behind trace DNA, which can confuse the scene. This happened in 2016, when a sloppy murder investigation in Germany had to be derailed in part by lab technicians who unintentionally smeared evidence with the DNA of an unrelated person [7].
The other problem is overdependence. The so-called “CSI effect” causes juries to anticipate that DNA is in every case or that DNA must therefore be decisive [8]. However, there is never a 100 percent in science; there are probabilities, and contexts are important.
Interpretation is also another issue. An example of this is that in DNA, which is in very small amounts, these can give ambiguous results. What about when there is disagreement amongst the experts, whose analysis is to be believed?
Outside the lab, the ethical considerations come into large proportions. Are all people supposed to have their DNA stored? How do we think about consent, particularly in those colonized communities that are targeted more than others? So, what is the trade-off between privacy and matters of public safety?
Such a powerful tool is DNA, yet with irresponsible hands, it can turn into a weapon.
Global Impact, Forensics Crossing Borders
DNA testing may be a regular procedure in first-world countries. However, there is a lack of forensic infrastructure in most corners of the world. Yet there are countries with no accredited forensic laboratories, no national databases, or there is no framework for DNA evidence in the law.
This rift has an influence on justice as well as closure. In Pakistan, the reason is an illustration in that in some high-profile rape and murder cases where victims could not be traced out after years, DNA technology was introduced in the country.
An example was the rape and murder of a 7-year-old called Zainab Ansari in 2018. When public outrage compelled authorities to use DNA and identify and convict the offender, Imran Arshad was identified and convicted; it turned out to be true that science, when used properly, can bring people back on track regarding the system [9].
Another area worldwide where DNA has found a home is in identifying the victims of mass-scale disasters and victims of war crimes-whether the tsunami of 2004 or genocide in Bosnia. In this case, DNA not only answers injustice, but also answers humanity.
Bridging the Gap: Popularizing Forensics to the Common Man
Forensic science is one of the most famous sciences and at the same time one of the most enigmatic sciences, as discussed and covered with jargon, myths, and media misdirection.
Such TV shows as CSI or Bones are already unrealistically simple: they show instant results, dramatic reveals, and scientists solving the cases with a single effort. As a matter of fact, analysis of DNA may require several weeks, and the cases frequently depend on the cooperation of lab technicians, lawyers, investigators, and medical examiners.
This is a gap that can be closed by ensuring that the field of forensic science becomes user-friendly and approachable. That is why such websites like this article are so important, as science communicators in general.
It requires more correct media images, displays of body parts, documentaries in the streets, and lessons in schools. When individuals know the processes of science, they will have more reasons to trust it as well as be more capable of challenging it when they need to.
Since justice does not exist in a vacuum. It exists in the communities, in the courts, and in the communication.
When Blood Speaks, Justice Listens!
Still thinking about Gary Doston?
Okay, let’s go back to the case of Gary Dotson. It was not merely a case of wrongful conviction, but a case of revolution. Moving away from assumptions to evidence. Rather than word of mouth, the solid science. In a world where there is prejudice, misdirection, and skepticism, forensic science brings the same candid and basic truth.
DNA says the truth, on behalf of the innocent, the forgotten, and the voiceless.
Blood never tells lies. It remembers. It reveals. It redeems.
It is good to allow the evidence to speak and justice to prevail.
References:
- https://www.law.northwestern.edu/legalclinic/wrongfulconvictions/exonerations/il/gary-dotson.html
- Lazer, D. (Ed.). (2004). DNA and the criminal justice system: The technology of justice. MIT Press.
- Gefrides, L. A., & Welch, K. E. (2006). Serology and DNA. In The Forensic Laboratory Handbook: Procedures and Practice(pp. 1-33). Totowa, NJ: Humana Press.
- https://www.bbc.com/news/uk-england-leicestershire-69023473
- Gymrek, M. (2017). A genomic view of short tandem repeats. Current opinion in genetics & development, 44, 9-16.
- Peschel, O., Kunz, S. N., Rothschild, M. A., & Mützel, E. (2011). Blood stain pattern analysis. Forensic science, medicine, and pathology, 7(3), 257-270.
- https://time.com/archive/6946145/germanys-phantom-serial-killer-a-dna-blunder/
- Shelton, D. E. (2008). The’CSI Effect’: Does It Exist?. National Institute of Justice Journal, 259.
- https://www.bbc.com/news/world-asia-45885686
More from this author: When Science Meets Silence: Decoding Post-Mortem Techniques in the Humaira Asghar Investigation
Anam Ilyas holds an MS Forensic Chemistry from Government College University, Lahore. She is a science enthusiast with a great love for explaining complex topics in simpler ways. She aims to bridge the gap between scientific research and the general public through her writing. When she is not writing or talking, you can find her lost in a book or making ideas come alive through her drawings.
