Identification PDF

IDENTIFICA TION DR MAGDE BOUKHATWA Definition; It is the recognition of an unknown person (living, dead or body remains) through certain features and characters which differentiate him from all others.  Classification a) Complete. b) Partial. Complete identification means the...

IDENTIFICA TION DR MAGDE BOUKHATWA Definition; It is the recognition of an unknown person (living, dead or body remains) through certain features and characters which differentiate him from all others.  Classification a) Complete. b) Partial. Complete identification means the absolute fixation of the individuality of a person. Partial identification means ascertainment of only some facts (sex, age, race, stature) about the identity while others remain still unknown. Types 1- Legal identification: It is complete description of an unknown dead body in order to know the identity of this person later on. It is required in: a)Cases of fire, explosion, travel accidents. b)Unknown dead body found on the road, in the fields, railway compartment or in water. c)In cases of decomposed bodies, mutilated bodies or in skeletal remains. 2- Personal or civil identification: It is recognition of a dead body or living person by his relatives, friends or witness, in front of civil courts e.g. in inheritance, missing persons, disputed paternity. 3- Criminal identification: a) It is the job of the police. b)It comprises dactylography, photograph, lip prints and foot prints and by DNA. c)It is required in cases of murder, rape, impersonation, interchange of newborn. Role of forensic doctor in case of unidentified bodies and/or assailants: 1. Take identification photos. 2. Chart and x-ray the teeth. 3. Fingerprint the body. 4. Perform total body x-rays. 5. Retain tissue for DNA. 6. Bite marks should be a- First swabbed to obtain saliva. b- Then they should be recorded by color photography. c- If there’s an impression, measurements and latex cast can be made of it to be matched against the teeth of a suspect or a victim. 7. Keep the clothes in a paper bag after allowing it to dry in air. 8. Take a swab from any obvious stain. 9. Collect any foreign hairs and obtain finger nail scrapping. Summary of Identification The points to be noted for identification:- 1. Race. 2. Sex. 3. Age. 4. Complexion and Features. 5. Hair. 6. a)Dactylography or Galton’s system of Finger Prints b) Lucards System or Poroscopy. c) Lip prints. d) Foot Prints. 7.Deformities and Birthmark. 8.Scars. 9.Tattoo marks. 10.Occupational marks. 11.Hand Writing. 12.Clothes, ornaments and articles in pocket. 13.Speech, Voice and language. 14.Gait. 15.Manners and Habits. 16.Mental power, memory and education. 17.Stature and weight. 18.Teeth, Dentures, filled cavities. 19.Genetics.  GALTON SYSTEM OF DACTYLOGRAPHY Fingerprints : The most accurate and reliable method of identification. A finger print means an impression made by the ball of the finger. It is based on the principles that the skin of the balls of the fingers and thumb is covered with papillary ridges with pores of the sweat glands.  Types of fingerprints a. Arches. b. Loops. c. Whorls. d. Composite. Loop: 60-70% of fingerprints patterns are loops. These are the most common fingerprint pattern. Whorl: 25-35% of fingerprint patterns are whorls. Whorls have at least two deltas and a core. Any fingerprint pattern that contains equal or more than 2 deltas will be a whorl pattern. DELTA: The point on a ridge at or in front of and nearest the center of the divergence of the type lines. The delta area is located as a triangular area where the ridges radiate outward in three directions. Arch: Only a few, that is close to 5% have this type of fingerprint. An arch doesn’t have any delta lines, or cores.. GENETIC MARKERS Is a gene or DNA sequence with a known location on a chromosome that can be used to identify individuals or species. Analytical methods to detect different types of genetic markers: The human ABO blood groups were discovered by Austrian-born American biologist Karl Landsteiner in 1901. The application of knowledge of the ABO system in blood transfusion practice is of enormous importance, since mistakes can have fatal consequences. Typing of blood group systems: They are red cell surface antigens that are permanent throughout life except some temporary changes after blood transfusion, so don’t do blood grouping except after at least 3 months post-transfusion. They include: ABO system: There are 3 antigens (A,B,O) giving 4 phenotypes (A, B, AB, O) due to 6 genotypes (AA, AO, BB, BO, AB, OO). ABO system locus is located on chromosome 9.  Rh system: It is present in 85-90% of persons hence they are expressed as Rh +ve, the remaining are Rh -ve. Their specific locus is located on chromosome 1. There are 3 pairs of genes; C,c , D ,d , E,e each gene codes for an antigen except d which means absence of D antigen. The individual may be : Rh +v e: due to presence of D antigen on RBCs (genotype is DD or D d). Rh-ve: due to absence of D antigen on RBCs (genotype is d d). Bloodstain evidence is most often associated with violent acts such as assault, homicide, abduction, suicide or even vehicular accidents. Analyzing the size, shape, distribution, overall appearance and location of bloodstains at a crime scene helps investigators by answering basic questions. Typing of red cell isoenzymes: Group of enzymes are present inside RBCs which catalyze various vital biochemical reactions. They show polymorphism (present in different forms in different people) hence the term isoenzymes. e.g: 1-Acid phosphatase (AP). clinically useful tumor marker.( ) 2-6 phosphogluconate dehydrogenase (6 PGD).( ) 3-Carbonic anhydrase (CA). Typing of serum protein systems e.g.: Haptaglobins (HP). Transferrin (Tf). Protease inhibitor (PI). Immunoglobulin markers (Gm, Km). Typing of hemoglobin: Fetal hemoglobin (HbF) is present in the fetus and very young infants. Sickle cell hemoglobin (HbS)which is responsible for sickle cell anemia, it is almost present in blacks. HbC: normally present in black people. Hb D, E, A (adult Hb). HLA typing (Human leucocyte antigens or complex) It consists of protein substances (about 50 antigens) on the surface of all cells including leucocytes on which they were first discovered. Coding genes for HLA antigens are assigned to the short arm of chromosome 6. DNA fingerprinting (DNA profiling, DNA typing DNA is the basic genetic material contained in all living cells(human, animal, plants, fungi, bacteria and viruses). It guides the cell in production of proteins. It is the material of which the chromosomes are made. Sources of Samples analyzed for DNA profiling; DNA can be extracted from: 1. Blood (WBCs). 2. Semen. 3. Saliva (wet or dry) found on chewing gum cigarette butts, postage samples, human skin (bite, suckling, kissing) or clothes. 4. Nasal secretions found in used handkerchiefs. 5.Hair roots (hair shaft is typed for mitochondrial DNA). 6. Skin cells found in fingernail scrapings, gloves, a cap or arm pit area of a shirt. DNA profiling: The identification of variable characteristics at one or more loci in an individual's DNA, and the comparison of those characteristics with other DNA samples to determine whether they could have the same origin. Locus: The site on a chromosome where a gene or other feature of the DNA is located. Each gene is presented by two alleles that may be similar (homozygous) or different (heterozygous).  embryo come from the mother’s egg. The father’s sperm contributes only nuclear DNA. While older biological samples that lack nucleated cellular material, such as hair, bone and teeth can not be analyzed with STR and RFLP, but they can be analyzed with mtDNA. Comparing the mtDNA profile of unidentified remains with the profile of a potential maternal relative can be an important technique in missing person investigations. A Short Tandem Repeat (STR) analysis is one of the most useful methods in molecular biology which is used to compare specific loci on DNA from two or more samples. A short tandem repeat is a microsatellite, consisting of a unit of two to thirteen nucleotides repeated hundreds of times in a row on the DNA strand. STR analysis measures the exact number of repeating units. This method differs from restriction fragment length polymorphism analysis (RFLP) since STR analysis does not cut the DNA with restriction enzymes. Instead, probes are attached to desired regions on the DNA, and a polymerase chain reaction (PCR) is employed to discover the lengths of the short tandem repeats. Medico-legal importance of genetic markers 1. Disputed paternity: a - Conventional serologic tests can only exclude a man from being the father of a child. b -DNA finger printing: it is possible to prove beyond any doubt whether a man is or is not the father of a child. Disputed paternity claims arise in the following: When husband denies that he is the father of the child. In cases of rape or if child is born out of lawful marriage and the accused person denies. When a woman pretends pregnancy& delivery and adopts a child for sake of inheritance. 2. Immigration cases: DNA finger print tests are done for immigration purposes to confirm the family relationships. 3. Criminal cases: Any stain (blood, semen or saliva) must be examined: At the scene of a crime. In threatening letters: traces of saliva from licking the envelope or stamp can be analyzed for its DNA profile and matched with the DNA pattern obtained from the suspect's blood sample. In sex crimes: Identification of assailant could be done by examining semen or swabbed bite marks for grouping (if he is secretor) as well as for DNA. 4. Identification of a missing person 5. Study of anthropology and ancient history: From mtDNA in Egyptians mummies and other ancient human remains. 6. Disputed maternity: When children are mixed in hospitals mitochondrial DNA is done. 8. In mass disaster: To help identification of people or remnants of bodies provided that reference samples are available. Estimation of age from bones The age of an individual can be determined from a combination of data provided by; A. Skull. B. Mandible and teeth. C. Appearance of ossify centers. D. Union of epiphyses. Skull; Dimensions: In mature infant the circumference of the head is 13 inches. Its length is 5 inches and its width is 4 inches. Fontanelles: Posterior fontanelle is closed at full term, Anterior fontanelle is closed at about 18-24 months after birth. Sutures: The condylar portion of the occipital bone fuses with the squamous portion at 3 years and with the basal portion at 5 years. Frontal suture closes at 3-5 years (except in negroid skull where it persists). The basioccipital and basisphenoid suture closes at 23 years.  The sagittal suture starts to close from the inner aspect at 25 years and is completely closed from the outer plate at about 30 years. The coronal suture closes about the age of 40 years. Lambdoid suture closes about the age of 50 years. At the age of 70 years, all skull sutures are closed and faint except the suture between the temporal and parietal bones which remains open until old age. Mandible and teeth: a) Mandible: In infants, the angle between the body of the mandible and the ramus is obtuse (small mandible that caries the milk teeth). The mental foramen near the lower border. In middle life, the angle becomes right. The mental foramen is midway between upper and lower border. The senile mandible has an obtuse angle again, the teeth are lost and the alveolar margins are absorbed. So, the mental foramen is higher. Milk teeth (temporary, primary or deciduous): 1) They are twenty in number (4 incisors, 2 canines and 4 molars in each jaw). 2) They are small, narrow, bluish white and delicate. 3) The first dentition (central incisors) begins at the 6th month.  Eruption ✓ Central incisors at 6th month ✓ Lateral incisors at 9th month ✓ First molars at 12th month ✓ Canines at 18th month ✓ Second molars at 24th month Permanent teeth (secondary): They are thirty two in number (4 incisors, 2 canines, 4 premolars or bicuspids and 6 molars in each jaw). They are big, broad, heavy and strong. Permanent incisors have usually serrated edges. The first erupted permanent tooth is the first molar (at 6 years) First molar 6 years Central incisor 7 years Lateral incisor 8 years First bicuspid 9 years Second bicuspid 10 years Canine 11 years Second molar 12 years Third molar(wisdom teeth) 18-25 years Appearance of ossify centers; Ossific center of the head of femur appears at end of the first year. Ossific center of the lower end of the radius appears at the end of the second year, it reaches 2/3 the breadth of the epiphysis at 7 years. Ossific center of the upper end of the radius appears at 6 years. Ossific center of the upper end of the ulna appears at 12 years. Union of epiphyses: 1) In the upper limb: A. Humerus: The trochlea unites with the capitulum at 14 years. They unite with the shaft at about 15 years. Lateral epicondyle unites with the shaft at about 16 years. Medial epicondyle unites with the shaft at about 17 years. Head of humerus unites with the shaft at about 20 years. b. Radius and Ulna: The upper end of the ulna and radius unite with the shaft of its bone at about 16 and 17 years respectively. The distal ends of both bones (wrist) unite with their shafts at about 20 years. c. Hands: The epiphyses of the metacarpals and phalanges unite with their shafts at about 18 years. 2) In the lower limb: a. Femur: The lesser trochanter, greater trochanter and head of the femur unite with the shaft at about 16, 17 and 18 years respectively. The lower end unites with the shaft at about 21 years. b. Tibia and Fibula: Lower end and upper end of the tibia and fibula unite with the shaft at about 18 (ankle) & 21 years respectively. c. Feet: The epiphyses of the metatarsals and phalanges unite with their shaft at about 18 years. 3) Pelvis: a. Hip bone: Pubic ramus unites with the ramus of the ischium at about 6 years. Ilium, ischium and pubic bones unite at about 14-15 years resulting in disappearance of the Y-shaped suture in the acetabulum. The epiphysis of the ischial tuberosity unites at about 21 years. The epiphysis of the iliac crest unites at about 23 years. b. Sacrum: Fusion of sacral segments starts between 20 – 24 years and completed at about 25 years. 4) Hyoid bone: The greater cornu of the hyoid bone unites with the body at about 40 years. 5) Sternum: Xiphoid process unites with the body of the sternum at about 40 years. The manubrium fuses with the body at about 60 years. 6) Clavicle: - The acromial end unites with the shaft at about 18 years. - The sternal end unites with the shaft at about 23 years.  Home work Describe in short the ages of medico-legal importance?