Post mortem changes

Question 1

Timing of death

Answer 1

• You might be able to time it in the first 18 hours
• You can measure body temperature but there are a lot of variables, there is a general rule that the body cools by a degree per hour

Question 2

Rigor mortis

Answer 2

• Stiffening and shortening of muscle fibres which results in rigidity
• Apparent after 5-7 hours
• Fully established by 8-12 hours after death
• Dissipates due to decomposition, frequently absent by 36 hours after death
• Body becomes flaccid again

Question 3

Main changes in body after death

Answer 3

• Rigor mortis
• Decomposition
• Putrefication
• Mummification
• Adipocere formation
• Skeletonisation
• Post mortem hypostasis
• Post mortem artefacts

Question 4

Putrefication

Answer 4

• Action of bacterial microorganisms, begins at death but takes a period of time to become detectible
• Variables such as ambient temperature, humidity, ‘cleanliness’ of the environment in which the body lies
• 2-3 days: discolouration of abdominal skin
• 1 week: blister formation and tissue swelling, including gas formation in body cavities
• Vascular marbling of superficial veins

Question 5

Mummification

Answer 5

• Process of ‘dry’ decomposition, dessication of the body and a relative lack of bacterial involvement
• Body essentially ‘dries out’, facial features and hands/feet rigid

Question 6

Adipocere formation

Answer 6

• Induced by the alteration of fatty tissue within the body into greasy/waxy or brittle material, may retain the body structure to some extent
• Tends to occur in damp or wet environments

Question 7

Skeletonisation

Answer 7

• When all soft tissues have completely degraded
• Process is extremely variable: meat-eating animals (post-mortem predation) and dipterous larvae
• Radioisotopes used to ‘age’ bones

Question 8

Post mortem hypostasis

Answer 8

• Pooling of stagnant blood in dependent regions of the body under the influence of gravity
• Readily apparent in external aspect and internal organs of the body
• Fully established after 6-12 hours
• You can see pressure pallor on where the pressure points on the body are
• Usually pink/purple in colour, cherry red in CO poisoning, red/brown with certain drugs

Question 9

Post mortem artefacts

Answer 9

• Resuscitation
• Animal predation
• Traumatic injury after death e.g. being dropped