Introduction
Forensic Onychology is a subfield of forensic science that studies and their possible evidential significance in criminal investigations. Nails, which are sometimes missed in typical forensic investigation, can provide critical information to assist solve cases.
Then is a detailed explanation of each content in forensic onychology
Nail description:
A nail is a hard, keratin- grounded structure at the tip of fritters and toes. It's composed of dead cells that are compacted together to form a hard, defensive subcaste.
Morphology:
Nail morphology includes,
1. Shape can be round, almond- shaped, or blockish.
2. Size can vary greatly between individualities.
3. Color can be pink, white, unheroic, or brown.
4. Texture can be smooth, ridged, or brittle.
5.Growth patterns Nails can grow sluggishly or snappily, and can be told by factors similar as nutrition and health.
Composition:
Nails are composed of,
1. Keratin - A protein that provides strength and severity to nails.
2. Water - The small quantum of water, which helps to keep them flexible.
3. Minerals - The small quantities of minerals similar as calcium, iron, and zinc.
4. Lipids - It contain small quantities of lipids, which help to keep them moisturized.
Two main types of nails:
1. Fingernails
Located on the fritters, these nails are generally lower and further delicate than toenails.
Fig.1.1 – Human Healthy Fingernail
2. Toenails
Located on the toes, these nails are generally larger and thicker than fingernails.
Structure of Nails:
A nail consists of several layers,
1. Nail plate: The visible, outer layer of the nail.
2. Nail bed: The area beneath the nail plate.
3. Cuticle: A thin layer of skin that overlaps the nail plate.
4. Nail matrix: The area beneath the cuticle where nail growth occurs.
Fig.1.3 - Nail diagram showing cuticle, nail plate, nail bed, and nail matrix
Conformation:
Nail conformation involves
1.Cell division - Cells in the nail matrix peak to form new nail cells.
2. Keratinization - New nail cells come compacted and hardened as they move towards the nail plate.
3. Isolation - Nail cells separate into different types, similar as nail plate cells and nail bed cells.
Shapes of nails:
Normal shapes :
1. Oval: Curved and symmetrical, with the tip being slightly narrower than the cuticle.
2. Almond: Similar to oval, but more pointed and narrower.
3. Square: Flat and wide, with no curve or tapering.
4. Round: Curved and symmetrical, with no sharp edges or points.
Fig.1.4 – Illustration of normal nail shapes: oval, almond, square, and round.
Abnormal Nail Shapes:
1. Clubbing: Thickening of the nail plate and curvature of the nail bed, often indicative of underlying medical conditions.
2. Koilonychia: Thinning and spooning of the nail plate, often caused by iron deficiency or other nutritional deficiencies.
3. Onychogryphosis: Thickening and hardening of the nail plate, often caused by aging or repetitive trauma.
4. Onycholysis: Separation of the nail plate from the nail bed, often caused by injury, infection, or nail biting.
Fig.1.5 g - Illustration of abnormal nail shapes: clubbing, spooning, pincer, and fungal-infected nails.
Other Nail Shapes:
1. Stiletto: Long and narrow, often seen in fashion or cosmetic nail enhancements.
2. Squoval: A combination of square and oval shapes, often seen in natural nail growth.
3. Bell-shaped: Curved and tapered, with the tip being narrower than the cuticle.
Fig.1.6 – Other nail shapes
Growth:
Nail growth rates vary
Fingernails Grow at an average rate of 0.1 to 0.2 mm per day.
Toenails Grow at an average rate of 0.05 to 0.1 mm per day.
Factors impacting growth: Nutrition, health, and age can all impact nail growth rates.
Conditions:
Nail conditions and diseases include,
1.Fungal infections :similar as onychomycosis.
2. Nail smelling :A habit that can beget nail damage and disfigurement.
3. Nail psoriasis :A condition that causes nail thickening, pitting, and abrasion.
Purpose :
Nails gives,
1. Nails cover the sensitive tips of fritters and toes from injury.
2. Nails contain whim-whams consummations that allow us to feel sensations similar as touch and pressure.
3. Nails help us to grasp and manipulate objects.
General Analysis:
General analysis of nails involves
1. Visual examination - Examining the nail's shape, size, color, and texture.
2. Microscope examination - Examining the nail's structure and composition using a microscope.
3. Chemical analysis - assaying the nail's chemical composition using ways similar as spectroscopy.
Forensic Significance
Forensic onychology involves assaying nails to prop in felonious examinations and legal proceedings.
Gender Estimation :
Researchers Bilkis Mitu and Lenka Halámková pioneered a groundbreaking forensic technique utilizing Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) to determine the sex of human nail samples, revolutionizing the field of forensic science and providing a valuable tool for investigators (2023).
Age Determination : A novel forensic approach pioneered by Kristina Fokias et al…enables accurate age determination through the analysis of DNA methylation patterns in fingernails and toenails, offering a valuable tool for investigators in estimating the age of unidentified human remains (2023).
Medicine Discovery : Roberto Scendoni's et al..groundbreaking study developed a novel, highly sensitive method for detecting morphine and opioids in fingernails, combining immunohistochemical analysis with ultra-high-performance liquid chromatography and high-resolution mass spectrometry, offering a valuable tool for forensic toxicology and substance abuse monitoring (2022).
DNA Profiling: Lisa M. Hebda, Ashley E. Doran, and David R. Foran's comparative study pioneered the optimization of STR analysis from fingernail DNA, demonstrating the feasibility of obtaining reliable genetic profiles from this challenging sample type, thereby enhancing the utility of fingernail evidence in forensic investigations (2014).
Bane Discovery : Joseph Salerno's pioneering work, "Nailing Drug & Alcohol Testing," introduced a revolutionary approach to substance abuse detection, utilizing fingernail and toenail samples as a non-invasive, highly accurate, and reliable means of testing for drugs and alcohol (2022).
Time Since Death : (A, 2006) A. Piccinini et al.. groundbreaking research demonstrated the feasibility of forensic DNA typing from human nails even in advanced stages of decomposition, providing a valuable tool for investigators to identify human remains in challenging and degraded conditions (2006).
Particular Identification : Adekunle O. George's innovative research introduced a simple, low-cost method for personal identification in resource-limited settings, leveraging unique characteristics of fingernail plate shape and size as a distinctive biometric marker (2005).
Health Condition: Sneha Gandhat et al... Conducted the fundamental way of disease detection in the human body using the nail image of human fingers and using the data from the image on the basis of nail colour is elaborated in this paper (2016).
Occupational History: Nidhi Kamra's study on nail changes in construction site workers demonstrated a significant correlation between prolonged exposure to workplace hazards and nail damage, highlighting the need for targeted interventions to promote occupational health and safety (2020).
Nails can be a valuable source of forensic evidence:
1.Sexual assault cases: Nail evidence can be used to link a suspect to the victim or crime scene.
2.Child and elder abuse cases: Nail evidence can be used to identify a suspect who may have scratched or torn their nails while abusing the victim.
3.Gang-related crimes: Nail evidence can be used to identify gang members who may have scratched or torn their nails during the commission of a crime.
4.Domestic violence cases: Nail evidence can be used to identify a suspect who may have scratched or torn their nails during a domestic dispute.
5.Mass disaster scenes: Nail evidence can be used to identify victims and help reconstruct the events surrounding the disaster.
Case Study: 01
The Murder of Julia Wallace( 1931)
Location :Liverpool, England
Case Details:
Julia Wallace, a 46- time-old woman, was set up boggled in her home. Her hubby, William Wallace, reported the crime and claimed that an meddler had committed the murder.
Fig.1.7- Julia Wallace and William Wallace
Fig.1.8 - Crime scene
Disquisition:
The police disquisition revealed that William Wallace had a solid justification, but the forensic substantiation refocused to him as the high suspect.
Nail substantiation:
During the disquisition, a torn piece of fingernail was set up on the bottom near the victim's body. The nail was latterly matched to William Wallace's fingernail.
Forensic Analysis:
The nail was examined by forensic experts, who set up that it matched William Wallace's fingernail in terms of shape, size, and color. The experts also set up a small quantum of skin cells on the nail, which matched William Wallace's DNA.
Conclusion:
Grounded on the nail substantiation and other forensic findings, William Wallace was arrested, charged, and condemned of his woman 's murder.
Significance:
This case study highlights the significance of nail substantiation in forensic examinations. The torn fingernail set up at the crime scene handed a pivotal link between the suspect and the crime, eventually leading to the conviction of the perpetrator.
Recent advancements in forensic science:
Nail as a Biometric Tool: Nails can be used to identify individuals, much like fingerprints. Researchers are exploring ways to use nail patterns, shape, and size to create unique biometric profiles.
Nail Growth Analysis: By analyzing nail growth patterns, investigators can estimate the time since death, which can be crucial in forensic investigations.
Environmental Contamination: Nails can absorb environmental contaminants, such as explosives, accelerants, or other hazardous substances. This can help investigators link suspects to crime scenes.
Conclusion:
Forensic onychology is a precious tool in felonious examinations, furnishing information on an existent's identity, health, and conditioning.
References
A, P. (2006). Forensic DNA typing of human nails at various stages of decomposition. International Congress Series, 1288, 586-588.
Fakias, K., Direckx, L., Voorde, W., & Bekaert, B. (2023). Age determination through DNA methylation patterns in fingernails and toenails. Forensic Science Iternational, 64.
George.A. (2005). finger nail plate shape and size for personal identification.
Hebda, L., Doran, A., & Foran, D. (2014). Collecting and Analyzing DNA Evidence from Fingernails. J Forensic Sci.
Kamra, N., & Sardana, S. (2020). nail changes in construction site workers. International Journal Of Research In Medical Science, 84-88.
Mitu, B., Halamkova, L., & Trojan, V. (2023). Sex Determination of Human Nails Based on Attenuated Total Reflection Fourier Transform Infrared Spectroscopy in Forensic Context. sensors.
ottens, & Ottens, R. (2015). DNA profiles from fingernails usingdirect PCR. Forensic Sci Med Pathol.
Palmari.A. (2000). drugs in nails :physiology pharmacokinetics and forensic toxicology.
Sagar.G. (2021). Nail as evidence in forensic toxicology.
Written by:
1.Ms. Bhuvaneshwari P
Student – M.Sc. Forensic Science Technology
School of Allied Health Sciences, Vinayaka Mission’s Research Foundation, Salem- Tamilnadu
2.Mr. Mohan S
Assistant Professor – Department of Forensic Science Technology
School of Allied Health Sciences, Vinayaka Mission’s Research Foundation, Salem- Tamilnadu