Determining the time of death
• Forensics is the use of science in the investigations of criminal activities
- It involves the collection and analysis of evidence from a potential crime scene
• Determining the time of death of a body is a very important component of forensic science
- It can be used during a police investigation to provide information about the circumstances.
surrounding the death of a person
• In order to accurately estimate time of death, there are several factors that must be established:
1. Extent of decomposition
2. Degree of muscle contraction
3. Body temperature of the diseased
4. Forensic entomology The rate of decomposition will be affected
N
5. Stage of succession by factors such as temperature and availability
of oxygen - slower in anaerobic conditions and
1. Extent of decomposition lower temperatures
• Tissues start to break down due to the action of enzymes
- Autolysis involves the body’s own enzymes
- Bacteria from the gut and lungs also invade tissues and release enzymes
- Loss of oxygen favours the growth of anaerobic bacteria
• Colour changes (due to sulfhaemoglobin in the blood)
- Greenish discolouration of the skin in the lower abdomen. Occurs between 36 and 72 hours
-
- Spreads and darkens to reddish green. after death
- Then purple black
• Gas or liquid blisters may appear on the skin Occurs after about a week
W
• Bacteria produce gases: hydrogen sulphide, methane, carbon dioxide, ammonia and hydrogen
- Body becomes bloated and smells
- Then gases are released and the body deflates
• As fluids drains away, the soft tissues shrink and the decay rate of the dry body is reduced
• Forensics is the use of science in the investigations of criminal activities
- It involves the collection and analysis of evidence from a potential crime scene
• Determining the time of death of a body is a very important component of forensic science
- It can be used during a police investigation to provide information about the circumstances.
surrounding the death of a person
• In order to accurately estimate time of death, there are several factors that must be established:
1. Extent of decomposition
2. Degree of muscle contraction
3. Body temperature of the diseased
4. Forensic entomology The rate of decomposition will be affected
N
5. Stage of succession by factors such as temperature and availability
of oxygen - slower in anaerobic conditions and
1. Extent of decomposition lower temperatures
• Tissues start to break down due to the action of enzymes
- Autolysis involves the body’s own enzymes
- Bacteria from the gut and lungs also invade tissues and release enzymes
- Loss of oxygen favours the growth of anaerobic bacteria
• Colour changes (due to sulfhaemoglobin in the blood)
- Greenish discolouration of the skin in the lower abdomen. Occurs between 36 and 72 hours
-
- Spreads and darkens to reddish green. after death
- Then purple black
• Gas or liquid blisters may appear on the skin Occurs after about a week
W
• Bacteria produce gases: hydrogen sulphide, methane, carbon dioxide, ammonia and hydrogen
- Body becomes bloated and smells
- Then gases are released and the body deflates
• As fluids drains away, the soft tissues shrink and the decay rate of the dry body is reduced
