Unit 4<br />Revision<br />Forensic Science<br />
What clues does a dead body leave behind?<br />
1. Extent of decomposition<br />
2. Extent of rigor mortis<br />
3. Temperature<br />
4. Entomology<br />Which insects (usually fly larvae) are living in the dead tissue<br />What stage of development have th...
What clues does a dead body leave behind?<br />
Why brain cells stop functioning immediately after death?<br />
How does rigor mortis takes place?<br />Muscle cells have large stores of ATP and glycogen and can continue to respire ana...
How quickly rigor mortis can sets in?<br />Rigor mortis depends on the level of ATP in muscles at the time of death.<br />...
Rigor mortis is also affected by the temperature of the surroundings.<br />Rigor mortis is not permanent — it usually pass...
To secure a prosecution for murder, a number of facts need to be verified.<br />• Who died, and who killed them.<br />• Wh...
	Temperature<br />Normal human body temperature is 37o C.<br />The metabolic reactions stops after death.<br />Heat is tra...
			Factors affecting body temperature<br />Outside of the body cools much more rapidly than the inside.<br />The amount of...
Cooling curve for bodies under known conditions are available.<br />From analyzing these curves and comparing it with the ...
Forensics
Forensics
Forensics
Forensics
Forensics
Forensics
Forensics
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Forensics

  1. 1. Unit 4<br />Revision<br />Forensic Science<br />
  2. 2. What clues does a dead body leave behind?<br />
  3. 3. 1. Extent of decomposition<br />
  4. 4. 2. Extent of rigor mortis<br />
  5. 5. 3. Temperature<br />
  6. 6. 4. Entomology<br />Which insects (usually fly larvae) are living in the dead tissue<br />What stage of development have they reached<br />
  7. 7.
  8. 8. What clues does a dead body leave behind?<br />
  9. 9. Why brain cells stop functioning immediately after death?<br />
  10. 10. How does rigor mortis takes place?<br />Muscle cells have large stores of ATP and glycogen and can continue to respire anaerobically for some time after death.<br />ATP is needed to maintain the muscles in a relaxed state. <br />As the muscle cells run out of ATP, the muscle fibres become permanently contracted and lock solid. <br />This produces a stiffening effect which is known as rigor mortis. <br />On average, rigor mortis starts about 2-4 hours after death <br />It needs between 6 and 8 hours to take full effect. <br />It begins in the muscles in the face and neck, progresses down the body, and spreads steadily to the larger muscles of the body.<br />
  11. 11. How quickly rigor mortis can sets in?<br />Rigor mortis depends on the level of ATP in muscles at the time of death.<br />The level of ATP varies from person to person depending on <br />· genetics <br />· level of fitness. <br />·level of activity before death. <br />For example, rigor mortis usually sets in very quickly in drowning victims. because they have used up all their muscle ATP struggling to stay afloat. <br />
  12. 12. Rigor mortis is also affected by the temperature of the surroundings.<br />Rigor mortis is not permanent — it usually passes between 36 and 48 hours after death.<br />The muscles soften as enzymes released from the lysosomes begin to break down the tissue. <br />
  13. 13. To secure a prosecution for murder, a number of facts need to be verified.<br />• Who died, and who killed them.<br />• What was used to commit the crime.<br />• When the victim died.<br />• Where the murder took place.<br />• Why the murder took place — the motive for the crime.<br />
  14. 14. Temperature<br />Normal human body temperature is 37o C.<br />The metabolic reactions stops after death.<br />Heat is transferred from body into the surroundings by radiation, conduction and evaporation of water.<br />The decrease in temperature gives an idea about the time of death.<br />
  15. 15. Factors affecting body temperature<br />Outside of the body cools much more rapidly than the inside.<br />The amount of body fat in the dead person affects the rate of cooling because it acts as insulation.<br />Clothing in the dead body will have an effect in losing temperature.<br />The immediate surrounding of the body can also affect temperature loss.<br />
  16. 16. Cooling curve for bodies under known conditions are available.<br />From analyzing these curves and comparing it with the dead persons data, it is possible to estimate the time of death.<br />

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