Forensic Identification of Human Identity

Forensic Identification (Human Identity)

• Forensic identity is defined as recognizing the individuality of a person, whether alive or deceased, using distinctive features that distinguish them from others.
• It can be categorized as: complete (positive) where full identity is possible; incomplete (presumptive) where only certain aspects of identity can be established; and legal identity where an unknown body is identified by symbols.
• Medico-legal investigators typically need to identify living people, fresh/intact corpses, decomposing bodies, mutilated/dismembered remains, and skeletonized material.
• Identification of unknown individuals is crucial in situations like impersonation, cases of comatose patients without identification, mentally impaired individuals, suspects in assault/rape/murder cases, mix-ups of newborns in hospitals, and disputes over paternity.
• Mass disasters such as air crashes, building fires, shipwrecks, and explosions create significant identification challenges; especially for high levels of putrefaction and mutilated bodies.

Methods of Identification

• General facial appearance, personal impression, and visual identification.
• Photography.
• Anthropometry.
• Handwriting analysis.
• Eye colour.
• Skin pigmentation and colour.
• Hair colour and structure.
• Fingerprints (dactylography), palm prints, foot prints, and lip prints.
• Other external features (scars, birthmarks, tattoos, occupational stigmata, diseases).
• Comparing antemortem records with the remains.
• DNA analysis (blood grouping, protein complexes, haptoglobins, blood enzymes, and DNA).

Fingerprints, Palm, Foot, and Lip Prints

• Fingerprints are formed by alternating ridges and grooves in the skin; specifically, in the epidermis and dermis of the distal phalanges.
• Fingerprint characteristics are unique and permanent except for cases of atrophy or impairment caused by certain diseases or radiation.
• Fingerprint analysis is based on unique features, such as precise ridge characteristics, and matching these to known prints, which allows for very accurate personal identification— a probability of 1/64 billion
• Fingerprint identification involves comparison of more than 16 points that exhibit similar features.
• Fingerprint analysis can also be performed using poroscopy.

Classification of Fingerprints

• Sir Henry Galton (1892) classified fingerprints into four main types:
  • Arch (approximately 6%)
  • Loop (Radial 3%; Ulnar 65%)
  • Whorl (approximately 25%)
  • Compound (approximately 1-2%)

Foot Prints

• Footprints can serve as pathways to identify missing persons or criminals.
• Footprints can be analyzed for distinguishing features, like congenital anomalies, distances between prints, and the presence of different movements, such as running,carrying heavy objects etc.

Identification of Dead Bodies

• Unmutilated corpses are identified using the same methods as living people, excepting gait, voice, and mental function, as well as handwriting.
• Presumptive identification of mutilated corpses involves visual assessment, anthropometry, personal data (race, sex, age), blood grouping, hair color, eye color, and tattoos.
• Positive identification involves comparing antemortem and postmortem records (dental records, fingerprints, palmprints, footprints, or DNA profiling).

Identification of Decomposed/Skeletalized Remains

• Determining if remains are bone/human bone using anatomical analysis and the precipitin test.
• Determining if remains belong to one person.
• Identifying the sex of the remains (skull and pelvis characteristics).
• Determining the age of the remains (skull sutures, dental analysis etc.).
• Determining the height of the remains, race etc.
• Determining the time since death or concealment, and
• Determining the cause of death.

Identification of Sex from Bones

• Skull characteristics (e.g., general size and shape, prominence of brow ridges, shape of the eye sockets, jaw size and shape).
• Pelvic characteristics (e.g., subpubic angle, shape and size of the sacrum, and the shape of the obturator foramen).
• Sternum.

Identification of Age from Bones

• Skull (dimensions, sutures, fontanelles, mandible, and teeth).
• Appearance of ossification centers.
• Union of epiphyses.
• Extent of the medullary cavity.

DNA Profiling

• DNA profiling was described by Dr. Alec Jeffreys, a British geneticist.
• DNA is highly specific to individuals due to unique, repetitive base sequences.
• DNA profiling is used in forensic investigations for personal identification, parentage testing, identifying body remains, and sex/species determination.

Medico-Legal Applications of DNA Typing

• Personal identification.

• Parentage testing.

• Identification and matching of body remains.

• Determination of sex and species.

Time Since Death

• Before 6 months: soft tissues are associated with the bones.
• 6-12 months: bones are attached by ligaments.
• After one year: only bone remains.
• Bones become lighter, whiter, less smelly, and more brittle over time.

Medical Imaging as an Aid for Forensic Identification

• Radiological studies are used to identify ages, injuries, and unique bone structures. Suitable areas include the wrist and elbow in infancy/childhood; the pelvis, hips, shoulder, and elbow joints in adolescence; and the skull in adulthood/old age.

Height and Weight Data

• Age determination based on height and weight tables according to age and sex.
• Height determination using span (between outstretched fingertips).
• Height determination via formulas based on bone measurements (e.g., femur = 25% of height, humerus= 18% of height).

This quiz explores the concept of forensic identification, including the definitions and categories of identity recognition for both living and deceased individuals. It covers the importance of identifying unknown persons in various scenarios, such as legal cases and mass disasters. Test your knowledge on this critical forensic topic.