Lectures in Forensic Medicine

LECTURES IN FORENSIC MEDICINE DNA FORENSICS DNA USES FOR FORENSIC IDENTIFICATION: 1. Identify potential suspects whose DNA may match evidence left at crime scenes 2. Exonerate persons wrongly accused of crimes 3. Identify crime and catastrophe victims 4. Establish paternity and other family relationships 5. Identify endangered and protected species as an aid to wild life officials-could be used for prosecuting poachers 6. Detect bacteria and other organisms 7. Match organ donors with recipients in transplant programs 8. Determine pedigree for seed or livestock breeds 9. Authenticate consumables such as caviar and wine

FORENSICS OF DROWNING Drowning- death caused by the filling of the lungs by liquid usually water, rendering breathing ineffective and leading to death due to asphyxia - Suffocation due to immersion of the nostrils and mouth in a liquid which is commonly water can occur in any liquid or some other chemical solution -originally conceived as suffocation due to mechanical obstruction of the airways by liquid -includes pathophysiological disturbance of the fluid and electrolyte balance Near drowning- initial survival of a drowning event and can lead to secondary complications including death later on Secondary drowning- death due to biological and chemical changes in the lungs after a near drowning incident or exposure to chemicals Oxygen starvation- a conscious victim will hold their breath and will try to access air, often resulting in panic including rapid body movement. This uses more oxygen in the bloodstream and renders victim unconscious -heart stops beating---cardiac arrest or clinical death---there is still chance of rescue---deterioration of brain cells---brain death---point of no return and victim is truly dead---on surface, the brain will die in approximately 6 minutes PHASES OF DROWNING: -Submersion----struggle which subsides with exhaustion and drowning---breath holding lasts until carbon dioxide accumulation stimulates respiration resulting in inhalation of water ---gulping of water coughing and vomiting---loss of consciousness---respiratory failure---heart failure ---death within 2-3 mins Survival rate from fatal salt water submersion is about 80% whereas in fresh water it is less than 50%.

EFFECTS OF IMMERSION: 1. Sinking, putrefaction and refloating -body in water usually sinks but because the specific gravity of a body is very close to that of water, but air trapped in clothing have a considerable effect on buoyancy -having sunk to the bottom, body will remain there until putrefactive gas formation decreases the specific gravity of the body---creates sufficient buoyancy---rises to surface and float -heavy clothing and weights attached to the body may delay but not usually prevent the body rising -temperature of water- principal determinant--- putrefaction is slower in cold water and in deep very cold water the body may never resurface -in the water, body floats face down---head lower than the rest of the body---lividity is most prominent on the head, neck and anterior chest and is irregularly distributed 2. Anserina cutis (goose skin)- roughening or pimpling of the skin 3. Maceration of the skin-blanched , swollen and wrinkled skin---palms and soles within 24-48 hrs 4. Post mortem injuries- abrasions, face, anterior trunk and extremities---water immersion leaches the blood out of antemortem wounds, while postmortem wounds tend to bleed more readily 5. Alcohol- 2/3rds of adult males found drowning have consumed alcohol 6. Fleas and lice-fleas associated with a body can survive up to 24 hrs submerged while lice can survive for 12-48 hrs 7. Body temperature- body cools in water about twice as fast as in air and reaches the temperature of the water usually within 5-6 hrs and nearly always within 12 hrs. FORENSIC INVESTIGATION IN DROWNING: -Mechanism of death in drowning is neither simple nor uniform Questions to resolve: 1. Did death occur prior to or after entry into the water?-was the victim alive or dead at the time of entry into the water? 2. Is the cause of death drowning? 3. If not, what is the cause of death? 4. why did the victim enter the water? 5. Why was the victim unable to survive in the water? Need to correlate the following information: 1. circumstances preceding the death—identification of the victim 2. circumstances of recovery of the body from water 3. autopsy and laboratory analyses -correct interpretation of findings and performance of some autopsy procedures is dependent upon a careful examination of the circumstances preceding death and of body recovery. -thorough police investigation -encompass environmental and human factors Human factors drowning ---implies that human deficiencies were the significant factor in the drowning episode like inexperience, poor judgment, intoxication

CIRCUMSTANCE AND MANNER OF DEATH IN DROWNING: 25%- occur in the sea 75%-occur in inland waters Majority of victims—young adults and children 2/3rd -accidental-uncovered fishponds, bath and swimming pools, alcohol consumption in males 1/3rd-suicidal- clothing left in a neat pile close to the water, pockets filled with stones or weights maybe tied to the body, hands and feet are tied to the body, concurrent drug overdose, slashing of the wrists, jumping from bridges or cliff into water will produce injuries such as fractures of the ribs, sternum, thoracic spine, lacerations of heart and lungs Homicide by drowning-rare—requires physical disparity between the assailant and the victim or a victim incapacitated by disease, drink or drugs or taken by surprise -disposal in water maybe attempted where the victim has already been killed by other means--victim of infanticide --autopsy is directed towards establishing injuries inconsistent with accident in the absence of signs of drowning

CAUSES OF DROWNING: 1. Alcohol consumption-impairs coordination and judgment 2. Boating incidents 3. Child abuse or neglect 4. Diving incidents 5. Falling through the ice of a body of water 6. Fatigue or exhaustion 7. Illicit drug use 8. Inability to swim 9. Incapacitating marine animal bite or sting 10. Having no life preserver 11. Failure to observe water safety rules 12. Muscle and stomach cramps 13. Scuba diving incident 14. Seizure, stroke, and heart attack while the victim is in the water 15. Sustaining a head and neck injury while involved with a water sport 16. Suicide attempt 17. Criminal intent 18. Unsupervised swimming