Identification I

Identification

• Identification: The determination of the individuality of a person based on certain physical characteristics.
  • Complete (absolute): Absolute fixation of the individuality of a person. ii.
  • Partial (incomplete): Ascertainment of only some facts (e.g. race, sex, age or stature) about the identity, while the others remain unknown.
• Identification is necessary in:
  • Living People
  • Persons accused of assault, murder or rape
  • Interchange of newborn babies in hospitals
  • Impersonation
  • Absconding soldiers and criminals
  • Marriage
  • Passport
  • Inheritance
  • Insurance claim
  • Missing person
  • Disputed sex
  • Dead people
  • In cases of fire, explosion and accidents.
  • When an unknown dead body is found on the road, fields, railway compartment or water.
  • In cases of decomposed body.
  • In cases of mutilated body.
  • Skeleton.
• Corpus delicti: The principle that it must be proven that a crime has actually occurred before a person can be convicted of committing the crime
• Race is determined by:
  • Clothing
  • Complexion
  • Eyes
  • Hairs
  • Skulls
• Cephalic Index: Index of breadth or cranial index.

Sex

• Sex: It is the biological term denoting the genetic, physiologic and anatomical characteristics of an individual, based on which we can identify ourselves into ‘males’ and ‘females’
• Gender: Sociological construct that denotes how an individual identifies according to social norms.
• Intersex: Intermingling of sexual characters of either sex in one individual to a varying degree including the physical form, reproductive organs and sexual behavior.
• In normal cases, in the living:
  • Most certain evidence of sex: Possession of ovaries in females, and testes in males.
  • Highly probable evidence of sex: Possession of sexual structures, e.g. developed breasts and vagina in females, and male distribution of hair and penis in males.
  • Presumptive evidence of sex: Outward appearance of individual features, contours of face, clothes, voice and figure.
• Sex determination is required for following reasons:
  • Identification in living: Sex is important in any chain of identity data and determination of the individuality of a person.
  • Participation in sports: Sex segregation in sports is based on the long-term endogenous androgen exposure of men at puberty that lead to the physiological gap with women.
  • For deciding whether an individual can exercise certain civil rights extended to one sex only.
  • For deciding questions relating to legitimacy, divorce, paternity, marriage, impotence, rape and affiliation.
• Identification of ‘sex’ of an individual may become problematic in:
  • Intersex: They may have features resembling one sex and the internal gonads could be of other sex or of both sexes (true hermaphrodite).
  • Transvestism: Individuals who cross dresses for sexual gratification.
  • Transgender: It is denoting or relating to an individual whose self-identity does not conform unambiguously to conventional notions of male or female gender.
  • Transsexuals: Individuals who have undergone sex change surgeries or sex reassignment.
  • Concealed sex: Individuals who hide their real sex for a motive by cross dressing.

Sex Verification Tests

• Physical morphology: External examination is done to determine the sex.
• Nuclear sexing or sex chromatin or microscopic test: Buccal epithelial cells or hair follicle cells are examined microscopically to detect the presence of ‘Barr body’.
• Gonadal biopsy: Detection of ‘internal gonads and sex chromosomes.
• Gene-based test: Polymerase chain reaction (PCR) is used to detect SRY gene and/or the DYZ1 region of Y chromosome which is diagnostic.
• Assay of testosterone levels: It also helps in differentiating the sex of an individual.

Nuclear Sexing

• Nuclear Sexing: It is a method of sexing cells which may help in determining sex in doubtful cases, decomposed and mutilated bodies and fragmentary remains
• Barr body (sex chromatin): It is the condensed, inactive, single X-chromosome found in the nuclei of somatic cells of most females and whose presence is the basis of sex determination tests that are performed.
• Davidson body: In females, neutrophil leucocytes contain a small nuclear attachment of drumstick form.
• Quinacrine dihydrochloride: Used for staining Y-chromosome that is seen as bright fluorescent body.
• Fluorescent Feulgen reaction: Using Acriflavin Schiff reagent is used for staining X-chromosome that is seen as bright yellow spot in nuclei.

Disorders of sexual development

• Ovotesticular DSD (true hermaphroditism): It is a rare condition; also known as double-sex or bisexual.
• Gonadal dysgenesis: It refers to a defect in gonad formation that is characterized by a progressive loss of primordial germ cells in the developing gonads of an embryo with consequent formation of hypoplastic and dysfunctioning gonads composed mainly of fibrous tissue—streak gonads.
  • Klinefelter syndrome: It is the most common sex chromosome disorder associated with male hypogonadism, most common presentation being 47XXY karyotype
  • Turner syndrome: It is the most common sex chromosome disorder associated with female hypogonadism with 45XO karyotype
  • Swyer syndrome: The individuals with pure gonadal dysplasia and a 46XY karyotype will display variable degrees of undermasculinization, dependent upon the amount of testicular dysplasia
  • Mosaicism: It is a genetic abnormality with mixture of cells with XX and XY, or X and XY sex chromosomes.
  • Mixed gonadal dysgenesis: It is a partial gonadal dysgenesis variant of Y chromosome mosaicism with 45XO/46XY karyotype, unilateral testis, a contralateral streak gonad, persistent müllerian ductal structures ipsilateral with the streak gonad, and varying levels of external genitalia undervirilization.
• Androgen receptor deficiency: Androgen insensitivity is caused by receptors that are insensitive to androgens, particularly testosterone.
  • Complete androgen insensitivity syndrome (CAIS): An X-linked recessive condition resulting in failure of normal masculinization of the external genitalia in genetically male (XY) individual.
  • Incomplete androgen insensitivity: The phenotype of individuals with partial androgen insensitivity syndrome may range from mildly virilized female external genitalia to mildly undervirilized male external genitalia with gynecomastia.
• 5-a reductase deficiency (5-ARD): This is an autosomal recessive sex-limited condition resulting in the inability to convert testosterone to dihydrotestosterone (DHT).
• Congenital adrenal hyperplasia (CAH): It is a condition wherein adrenal glands produce excessive amounts of testosterone in females.
• Marfan syndrome: An inherited connective-tissue disorder transmitted as an autosomal dominant trait.
• Down syndrome: The most common chromosomal disorder and the most common cause of intellectual disability that result from having an extra copy of chromosome 21.
• Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome: It is a congenital malformation characterized by müllerian duct agenesis.
• Kallmann syndrome: A rare hormonal condition of hypogonadotrophic hypogonadism.
• Noonan syndrome: It was thought to be a form of Turner syndrome, but patients with this syndrome have normal karyotype.
• Sheehan syndrome: It occurs due to necrosis of the pituitary gland with associated hypopituitarism resulting from postpartum hemorrhage and hypovolemic shock.
• Virilizing ovarian tumor: A rare cause of hyperandrogenism in women, and account for < 5% of all ovarian neoplasms.
• Ovarian dysgenesis: A rare type of female hypogonadism in which no functional ovaries are present to induce puberty in an otherwise normal girl whose karyotype is found to be 46XX.
• Dentigerous cyst: The second most common odontogenic cyst is the dentigerous cyst, which develops within the normal dental follicle that surrounds an unerupted tooth.

Sex from Skeletal Remains

• Recognizable sex differences appear after puberty except in pelvis. In pelvis, sex features are independent of each other and one may even contradict the other in same pelvis.
• The sex of long bones can be determined on the basis of medullary index from tibia, humerus, ulna and radius. Sternum is least useful
• Preauricular sulcus: The pelvic portion of the anterior sacroiliac ligament is attached to it.
• Chilotic line: It is an anthropometric line extending from the posterior aspect of the iliopectineal eminence to the closest point on the anterior auricular margin and then to the iliac crest.

Age

• Analyzing all age-related attributes is the best way to estimate age.
• Some of the utilized features include:
  • Dental eruption
  • Epiphyseal unions
  • Pubic symphyseal morphology
  • Cranial suture closures
  • Mandibular and sacral changes
  • Miscellaneous
  • Secondary sexual characters
  • Age-related degenerative conditions.
• Teeth eruption and calcification, Stack's method, Miles method, Boyde's method, and Gustafson's method can determine age.
  • Alveolar cavities which contain teeth are formed around the 3–4th month of intrauterine life (IUL).
  • At birth, rudiments of all the temporary teeth and the 1st permanent molars may be found in jaw.
  • Each tooth has a crown, neck and root embedded in jaw bone
  • Teeth are composed of dentin covered on the crown by enamel and on the root by cementum which is attached to the alveolar bone by a periodontal membrane.
  • Tooth enamel: It is the hardest substance in the body containing primarily hydroxyapatite.
  • Tooth formation proceeds in an invariable sequence.
  • Root mineralization begins after crown formation and ends with apical foramen reduction.
  • Deciduous dentition mineralizes early in the 2nd trimester, and third molar root formation may not be complete until 20 years old.
  • The deciduous tooth's root absorbs as the permanent tooth erupts, leaving only the crown.
• Super-added permanent teeth: These teeth do not have deciduous predecessors. All permanent molars belong to this category (6 in each jaw).
• Successional permanent teeth: These teeth erupt in place of deciduous teeth, e.g. permanent premolars erupt in place of deciduous molars (10 in each jaw).
• Estimation of age from teeth beyond 25 years
  • Miles’ method: The amount of wear on all three permanent molars occurs at comparable rates which can be assessed, and age estimation made on the basis of comparison to the baseline.
  • Gustafson’s method: Based on the evaluation of ground sections of teeth.
  • Aspartic acid racemization (AAR): A major non-enzymatic covalent modification that causes abnormal protein accumulation in many human tissues with age.
  • Chemical method: Estimation of nitrogen content of enamel, carbonate content and concentration of ions.
  • Radiocarbon dating of tooth enamel: It may give a precise estimation of an individual’s date of birth.
• Histological technique: It is based on the counting of incremental lines in dental cementum added to the average age of tooth eruption for the estimation of the age at death.
• Aspartic acid racemization: The analysis has been done on both tooth enamel and crown dentin with analysis of dentin giving more accurate age estimation than enamel.
• Gustafon’s Criteria
  • Attrition: Wearing down of occlusal surface due to mastication, first involving enamel, then dentin and lastly pulp.
  • Periodontosis: Retraction of gum margin and loosening of tooth exposing the neck and adjacent parts of roots.
  • Secondary dentin: Progressive infilling of the dental pulp cavity, decreases the size of cavity and may completely obliterate it.
  • Cementum apposition: Cementum increase in thickness around the root due to changes in tooth position, continuously deposited throughout life and forms incremental lines.
  • Root resorption: Involves both cementum and dentin. Starts at apex and extends upwards.
  • Root transparency: Occurs in root from below upwards in lower jaw and above downwards in upper jaw due to rarefaction of the dentin tissue. Most reliable of all criteria.
• Other Information from Teeth
  • Mandibular canines show the greatest dimensional differences with larger teeth in males than in females.
  • Optical scanner and radiogrammetric measurements of mandibular permanent tooth root length and crown diameter help determine sex.
  • Amelogenin (AMEL): A major protein found in human enamel.
  • Shovel-shaped: These upper central incisors can be found in most Mongoloids and Americans.
  • Carabelli’s cusp, taurodontism and enamel pearls have been listed as racial determinants.
  • Carabelli’s tubercle: An anomalous cusp on the mesial palatal surface of the upper first permanent molars, most commonly seen among Europeans
  • Taurodontism: A tooth abnormality with elongated pulp chambers and apical displacement of bifurcation or trifurcation of the roots, giving it a rectangular shape.

Temporary and Permanent Teeth

Eruption of Deciduous Teeth

Eruption of Permanent Teeth

Scars

• Scars: It is a fibrous tissue covered by epithelium without hair follicles, sweat glands or pigment, produced from the healing of a wound.
• Scars from lacerated wounds and infected wounds are firmer, irregular, prominent and attached to the deeper tissues.
  • Incised wounds: These wounds produce linear scars.
  • Stab wounds: Due to knife produces oval, elliptical, triangular or irregular scars which are depressed.
  • Bullet wounds: These causes a circular depressed scar.
  • Scars from scalds have spotted appearance.
  • Vaccination scars: These scard are circular or oval, flat or slightly depressed.

Tattoo Marks

• Tattoos: Designs made in the skin by multiple small puncture wounds with needles dipped in coloring matter which is attached to an oscillating unit.
  • Dyes used are Indigo, cobalt, carbon, vermilion, cadmium, selenium, Prussian blue and Indian ink.
• Traumatic tattoos: Resulting from injuries (roadside injuries) or close range firearm (unburnt gunpowder) or pencil lead; these are unintentional and unwanted tattoos.
• Amateur tattoos: Tattoo applied by anyone at home, using a needle and a single color carbon based ink, e.g. India ink applied at varying depths.
• Professional tattoos: This is created by a trained tattoo artist at a salon or tattoo parlor which contains several colors and applied uniformly beneath the skin.
• Cosmetic tattoos: They camouflage skin discolorations, such as birthmarks or scars, tattooing ‘hair follicles’ into bald areas or corneal tattooing in perforating injury.
• Medical tattoos: This type of tattoos is used for indicating a medically relevant condition or body location