What is Forensic Science?

By Marzia KhanReviewed by Lily Ramsey, LLM

Forensic science is a systematic scientific process used in criminal investigations to address legal questions.¹ It involves analyzing crime scenes, conducting autopsies, and performing laboratory tests. These techniques are applied to solve crimes, resolve civil disputes, enforce criminal laws and government regulations, and protect public health.²

Image Credit: Drazen Zigic/Shutterstock.com

Core Disciplines of Forensic Science

The primary fields within forensic science include (i) forensic biology and DNA analysis, (ii) forensic chemistry, (iii) forensic toxicology, (iv) forensic anthropology, and (v) forensic pathology.

Forensic Biology and DNA Analysis

DNA analysis has been used for forensic applications for more than 50 years, including the characterization of biological evidence such as hair, blood, semen, saliva, and urine.³ Biological substances left at a crime scene can be used to associate the samples to suspects and individuals involved through DNA analysis.⁴

Forensic Chemistry

Forensic drug chemistry plays a significant role in criminal investigations, which use scientific methods to detect, analyze, and interpret substances found at crime scenes. Additionally, these analyses can provide evidence that supports connections between substances, individuals, and criminal activities.

The primary objective of this field is to determine the presence and composition of controlled substances, including illegal and prescription drugs and medications, from samples found at crime scenes.⁵

The results of forensic chemistry analyses can impact the course of an investigation, influencing legal proceedings and decisions, as well as influencing the victims and suspects involved in the case.⁵

Forensic Toxicology

Forensic toxicology consists of a division of forensic science relating to investigating toxic substances and their impact on the body. This field is significant in criminal investigations, leading to information about the cause of death in suspicious cases.⁶

Forensic toxicology can also be used to detect poisons, alcohols, and other chemicals in biological specimens, with toxicologists working with other forensic experts to piece together hypotheses about a crime or death.⁶

Forensic Anthropology

Forensic anthropologists aim to provide positive scientific identification of human remains, including characterizing human study traits of skeletons and detecting the presence of orthopedic devices.⁷

To obtain a positive scientific identification, two things must be found: (i) evidence unique to the individual and (ii) being comparable to antemortem data available from the individual. The identification process has accelerated over the years through advanced supportive techniques such as radiographs, scans, and implants.⁷

Forensic Pathology

Forensic pathology consists of an area of medicine that connects science and law, with forensic pathologists examining the deceased for the cause of death, mechanism, and manner of death.⁸

Forensic pathologists are also used to evaluate and explain pathology issues that occur during criminal and civil cases and can provide testimony as expert witnesses.⁸

Key Techniques in Forensic Science

DNA Profiling

Popular forensic tools can vary depending on the intent of analysis, such as the use of DNA profiling, which has been developed to provide DNA evidence that is accurate and reliable.⁹

DNA profiling used in forensics aims to identify a person that is already known to investigators, with autosomal short tandem repeat (STR) profiles being produced from biological samples found at crime scenes, which can then be compared with known profiles.¹⁰

Fingerprint Analysis

Fingerprint analysis can be used in personal identification due to the minutiae in fingerprint patterns, which result from non-genetic events that occur during the embryonic development of the fingerpads.

This means even the fingerprint patterns of identical twins are different and can be distinguished, demonstrating the unique nature of each fingerprint pattern on individuals.³

Ballistics

Ballistics can be used to examine firearms, with the aim of presenting the findings in court, linking ammunition components with the weapon that was discharged. This area attempts to analyze the mechanical condition of firearms, establish the range of fire, as well as identify entry and exit wounds from the firearm, and interpret the damage.¹¹

While ballistics is a well-known area associated with crime scene investigations, it is a controversial field in reality, as there are only a few studies on firearms, which do not indicate that investigators can reliably determine if specific guns fired bullets or cartridges.¹²

The absence of standards for such firearm identification may lead to a higher probability of convicting the innocent, which has led to restricted firearm testimonies by courts.¹²

Trace Evidence Analysis

Trace evidence analysis comprises small physical evidence, such as hairs or fibers, that are found at crime scenes or transferred between individuals or objects.

Usually, these materials are microscopic in size but can provide significant information for the investigation, including (i) what may have happened, (ii) where the sample is from, and (iii) how the transfer occurred.¹³

Examiners of trace evidence use a range of analytical tools associated with microscopy, analytical chemistry, and informatics.¹³

Digital Forensics

Digital transformation has revolutionized the way we live, and it has also impacted how crime is carried out, with new technologies being used for criminal activities. This has led to the need for digital forensics to increase the capacity to meet the demands of cybercrimes.¹⁴

Police investigators and courts are increasingly using digital experts, and digital forensics provides significant tools and methods for handling electronic evidence, including the use of artificial intelligence (AI).

An example of the evolving nature of this field includes the use of AI and novel technologies for the European Forensic Science Area 2030 vision.¹⁴

Uses of Microscopy in Forensics

Applications of Forensic Science

While forensic science can be used in criminal investigations, such as through collecting evidence, identifying suspects, and solving criminal cases with scientific backing, it can also be used in various ways beyond crime-solving applications.¹⁰

Forensic science can be used for applications such as identifying victims of disasters, including mass disaster victims of natural disasters or accidents, with DNA analysis being a critical tool.⁹

It can also be used for wildlife crime, with wildlife forensics being used to solve illicit trade or criminal use of wildlife. This is important as wildlife biodiversity is declining significantly, and more species are being threatened with extinction. Poaching is a common example of wildlife crime that threatens species globally.¹⁵

Environmental forensics can also be used to analyze various environmental damage, including the source and release of contamination and chemicals within the environment. This field also aims to define the time frames of emissions and pollution.¹⁶

Recent Advances and Trends in Forensic Science

Many recent advances and trends in forensic science aim to evolve the field and provide high-level analyses for applications.

Next-generation sequencing (NGS) can be used to sequence full or partial genomes with a high level of accuracy. This relatively recent innovation has a high-throughput capacity, is low in cost, and has become a significant analytical tool for genomics.

Using this technology for forensics can enable DNA analysis to be a crucial tool, as traditional forensic DNA analysis can have limitations due to the use of highly degraded and contaminated samples. Due to this, NGS can be revolutionary for enhancing DNA accuracy and speed of analysis.¹⁷

Analysis of trace evidence by extracting DNA from minor contact transfer or touch DNA can also be used to strengthen scientific evidence in crime cases by playing a critical role in forensic laboratory work.¹⁸

Additionally, the advanced use of investigative genetic genealogy (IGG) can find a person of interest in criminal or even missing person cases when national DNA databases lead to unsuccessful candidates.

IGG examines 600,000 single nucleotide polymorphisms instead of the 20 STRs used in traditional forensic DNA testing, which can lead to linking relatives as distant third or fourth cousins, leading to solving cases by identifying an extended family tree.¹⁹

Portable forensic devices for on-site analyses are also an advancement that enables the lab to be brought onto the field, enhancing improvements to workflow and evidence collection.

Portable instrumentation has innovated environmental forensics, as well as other fields, enabling evidence to be studied in the field, which is especially significant when the component of interest cannot be taken to the lab for further study.¹⁶

Interestingly, the evolving nature of technology has led to AI and emerging technologies being used for solving crime, including cybercrime, as these innovative technologies are also used for criminal activities.¹⁴

How has DNA Analysis Evolved in Forensics?

Conclusion

Forensic science has an essential role in justice and ensuring public safety, with this very versatile field being used for many aspects of crime, from burglaries to murder and even cybercrime.²

Utilizing the various sub-divisions of forensic science, including DNA analysis, fingerprinting, and trace analysis, enables investigators to be thorough in their investigations.

References

1. Ireland T. What is Forensic Science? BBC Science Focus Magazine - science, nature, technology, Q&As. https://www.sciencefocus.com/the-human-body/what-is-forensic-science. Published December 8, 2020. Accessed November 17, 2024.
2. What is Forensic Science? https://www.aafs.org/careers-forensic-science/what-forensic-science. Published March 13, 2024. Accessed November 17, 2024.
3. Introduction. DNA Technology in Forensic Science. https://www.ncbi.nlm.nih.gov/books/NBK234533/. Published January 1, 1992. Accessed November 17, 2024.
4. DNA and Biological Evidence. Forensic Science. https://www.nist.gov/forensic-science/dna-and-biological-evidence. Published April 5, 2022. Accessed November 17, 2024.
5. Ikbal AM, Debnath R, Thomas S, Chattopadhyay D, Palit P. Forensic Drug Chemistry: Unravelling Evidence Through Scientific Analysis. Interdisciplinary Biotechnological Advances. May 2024:319-361. doi:10.1007/978-981-97-1148-2_16.
6. Shukla S, Khanna S, Gani Mir T ul, Dalal J, Sankhyan D, Khanna K. Emerging global trends and development in forensic toxicology: A Review. Journal of Forensic and Legal Medicine. 2024;103:102675. doi:10.1016/j.jflm.2024.102675.
7. Ubelaker DH, Shamlou A, Kunkle A. Contributions of Forensic Anthropology to Positive Scientific Identification: A critical review. Forensic Sciences Research. 2018;4(1):45-50. doi:10.1080/20961790.2018.1523704.
8. Tatsumi K, Graham M. Death Investigation in the United States: Forensic Pathology. Missouri Medicine. https://pmc.ncbi.nlm.nih.gov/articles/PMC9616451/. Published 2022. Accessed November 17, 2024.
9. Amankwaa AO, McCartney C. The Effectiveness of the Current Use of Forensics DNA in Criminal Investigations in England and Wales. WIREs Forensic Science. 2021;3(6). doi:10.1002/wfs2.1414.
10. Kayser M, de Knijff P. Improving Human Forensics Through Advances in Genetics, Genomics and Molecular Biology. Nature Reviews Genetics. 2011;12(3):179-192. doi:10.1038/nrg2952.
11. Understanding Ballistics: A Primer for Courts. https://royalsociety.org/-/media/about-us/programmes/science-and-law/royal-society-ballistics-primer.pdf. Accessed November 17, 2024.
12. Faigman DL, Scurich N, Albright TD. The Field of Firearms Forensics is Flawed. Scientific American. https://www.scientificamerican.com/article/the-field-of-firearms-forensics-is-flawed/. Published May 25, 2022. Accessed November 17, 2024.
13. Trejos T, Koch S, Mehltretter A. Scientific Foundations and Current State of Trace Evidence—A Review. Forensic Chemistry. 2020;18:100223. doi:10.1016/j.forc.2020.100223.
14. Klasén L, Fock N, Forchheimer R. The Invisible Evidence: Digital Forensics as Key to Solving Crimes in the Digital Age. Forensic Science International. 2024;362:112133. doi:10.1016/j.forsciint.2024.112133.
15. Jota Baptista C, Seixas F, Gonzalo-Orden JM, Oliveira PA. Wildlife Forensic Sciences: A Tool to Nature Conservation Towards a One Health Approach. Forensic Sciences. 2022;2(4):808-817. doi:10.3390/forensicsci2040058.
16. Mach PM, Verbeck GF. Analytical Methods and Trends in Environmental Forensics. Development and Environment. 2018:285-301. doi:10.1007/978-3-319-75935-7_11.
17. Yang Y, Xie B, Yan J. Application of Next-Generation Sequencing Technology in Forensic Science. Genomics, Proteomics & Bioinformatics. 2014;12(5):190-197. doi:10.1016/j.gpb.2014.09.001.
18. Sessa F, Salerno M, Bertozzi G, et al. Touch DNA: Impact of Handling Time on Touch Deposit and Evaluation of Different Recovery Techniques: An Experimental Study. Scientific Reports. 2019;9(1). doi:10.1038/s41598-019-46051-9.
19. Butler JM. Recent Advances in Forensic Biology and Forensic DNA Typing: Interpol Review 2019–2022. Forensic Science International: Synergy. 2023;6:100311. doi:10.1016/j.fsisyn.2022.100311.

Further Reading

• All Forensics Content
• Collecting Evidence at a Crime Scene
• Using Forensics to Tackle Child Exploitation
• Forensic Investigations of Natural Disasters
• Forensic Identification in Mass Disasters