CSI: What Do You Really Know About Forensic Science?
By Kate O’Flanagan
Most people have, at the very least, an awareness of forensic science; the discipline having entered the zeitgeist via crime fiction crime scene investigators in white PPE being shown on the news. But beyond these popular images, what does the general public really know about forensic science? What is the reality of this discipline? And how has its increasing presence in fiction impacted how people think about it?
The CSI Effect refers to the way in which the portrayal of forensic science on crime television shows influences public perception. First coined in a 2004 USA Today article, the phenomenon takes its name from the show CSI: Crime Scene Investigation (2000-2005). Though the original definition specifically referred to the belief that jurors have come to demand more forensic evidence in criminal trials, it can also be used in reference to the misconceptions surrounding forensic science held by the general public. The exaggerated, glamourised depictions of the discipline risk heightened, false expectation of what forensic science can deliver. While CSI has been criticised by scientists and legal professionals for its influence on public perception, it may also have had a positive impact. Over the five-year period from 2004-2009, the number of undergraduates studying forensic science and crime scene science in the UK more than doubled; a third of students taking the degrees said they had been inspired by TV coverage of the profession.
For as long as crimes have been committed, investigators have strived to use science to secure convictions. The first written account of using medicine and entomology to solve criminal cases is attributed to a book written in China in 1248 – the book of Xi Yuan Lu by Song Ci. As science has advanced across the centuries and scientific methods of inquiry have been standardised, forensic science as a whole has been improved, with new investigative techniques being adopted. This advancement also led to established forensic practices having been re-examined, with some being discarded completely.
Infamously, American serial killer Ted Bundy was convicted on the strength of bite mark evidence in 1979. Bundy bit one of his victims, Lisa Levy, twice. The first bite showed a full and complete bite mark while the second was rotated and gave two impressions of his lower teeth. Photographs and impressions of the wounds were compared to castings of Bundy’s teeth and deemed a match; both indicated a distinctly crooked bottom set of teeth and a chipped left incisor with three peaks. Combined with eyewitness testimony, this was enough for Bundy to receive the death sentence.
We know, undoubtedly, that Ted Bundy was guilty. He ultimately confessed to thirty murders committed in seven states between 1974 and 1978, though his true victim count may be higher. However, if his trial were held today, the bite mark analysis would not be enough to convict. The discipline has drawn increasing criticism since the ‘90s. Used in legal proceedings since 1870, it is based on two hypotheses: Every person’s teeth leave a unique bite mark, and human skin is capable of preserving those marks in such a way that they can be definitively matched to a specific person. A lack of empirical evidence supporting these hypotheses, and up to two dozen convictions based on bite marks being overturned due to DNA evidence, has seen bite mark analysis largely abandoned and condemned by several scientific bodies.
Forensic dentistry as a whole is not unfounded, however. It remains a useful tool in the identification of unidentified human remains. In the aftermath of the 2004 Indian Ocean tsunami, dental records were the primary identifier for 46.2% of identified victims. As for bite marks, in some cases, they may prove forensically useful by providing assailant DNA in the form of saliva or blood.
The core tenets of forensic science as it stands today are forensic chemistry and forensic biology. Peer-reviewed, validated chemical and biological analytical techniques are used throughout the discipline – chromatography for explosives analysis, spectroscopy for drugs of abuse, polymerase chain reactions (PCR) for genetic fingerprinting. As technology and science have improved and developed, non-traditional matrices such as saliva, human nails, and hair have become valuable sources of toxicological information, as well as DNA.
Forensic genealogy has emerged as a rapidly growing field in forensic science. It first came to public attention in 2018 when it was used in the successful identification and arrest of Joseph James DeAngelo Jr, the Golden State Killer. It can be used to identify perpetrators of violent crimes, as well as unidentified human remains. The process involves uploading a crime scene DNA profile to a genetic genealogy database to trace, and ultimately place the unknown sample within, its corresponding family tree. This identification is done through analysis of identity-by-descent sections of DNA that indicate shared ancestors. As of September 2020, forensic genealogy has led to the discovery of over 150 suspects of murder and sexual assault.
Technological advancements have resulted in devices that were once constrained to the lab due to size are now portable, often handheld, and can be brought to the scene of the crime for in situ analysis. While this cuts down on the sample processing time, it may raise questions about the quality of analysis. Specialised technology increases the need for highly trained scientists due to the potential implications of substandard analysis being performed. But, in Ireland and across the world, the forensic scientists are not always present at the scene.
Forensic Science Ireland (FSI), originally the Forensic Science Laboratory, was established in 1975 to provide a scientific service to the Criminal Justice System via analysis of crime scene samples and providing evidence in criminal trials. In its early years, it was customary for a forensic scientist to also carry out a crime scene examination. This has fallen to the wayside as Ireland has adopted a two-step approach to forensic investigation.
When a crime occurs, Crime Scene Examiners (CSEs), trained members of An Garda Síochána, are dispatched to the scene. They take fingerprints, photograph the scene, and seize any samples or exhibits present. The evidence collected is then transported to the FSI laboratory where it is analysed by the forensic scientists there. Adopted for efficiency reasons, the two-step approach has led to a level of separation between CSE and scientists. This results in the scientists carrying out the analysis lacking the all-important context of where and how the samples were collected. The context is critical in forensic investigations as it can inform where and what types of evidence is looked for and how the results fit into the bigger picture. Stronger links between CSEs and scientists would illuminate this context and increase the efficiency of both forensic collection and analysis.
However, problems also arise from full integration. Outside of Ireland, funding issues have led to police forces forgoing forensic scientists entirely and carrying out their analysis in-house. This drastically lowers the quality of analysis being done as not all police scientific facilities are internationally accredited, nor are all members of the police specially trained scientists. Greater levels of confirmation bias have been observed in cases where police handle the forensic analysis. How impartial is the scientific evidence if it was analysed and presented by the party that benefits from a conviction? A 2009 report by the National Academy of Sciences (NAS) in the United States recommended that forensic science should be removed from the administrative control of the police and prosecution. While all external suppliers of forensic services were already obliged to have accreditation, the NAS also recommended that there should be mandatory accreditation of all forensic laboratories and certification of all forensic practitioners.
Forensic science is an ever-evolving discipline. Sitting at the intersection of science and the law, it is impacted by both scientific innovation and legal doctrine. The marriage of these two disciplines creates unique challenges for forensics. The legal world moves much slower than the scientific world; the criminal justice system must keep pace with scientific advancements in order to implement scientifically robust methods to analyse and collect evidence. While it may not be the ‘magic bullet’ it is presented as in popular fiction, forensic science is an integral and important tool in criminal investigations.