POSTMORTEM CHANGES & TIME OF DEATH

Discussion in 'JonBenet Ramsey' started by tipper, Feb 5, 2006.

  1. tipper

    tipper Former Member

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    I thought this was an interesting article. Its the first I've read that makes specific mention of children. (Emphasis is mine.)

    http://www.dundee.ac.uk/forensicmedicine/llb/timedeath.htm

    POSTMORTEM CHANGES AND TIME OF DEATH
    […]
    There is great variation in the rate of onset and the duration of rigor mortis.

    Niderkorn's (1872) observations on 113 bodies provides the main reference database for the development of rigor mortis and is commonly cited in textbooks. His data was as follows (Ref. 19 at p. 31):

    Number of Cases


    Hours Post Mortem at which Rigor was Complete
    […]
    {Couldn't get the table to copy}

    In this series, rigor was complete in 14% of cases at 3 hours post mortem and this percentage had risen to 72% at 6 hours and to 90% at 9 hours. By 12 hours post mortem rigor was complete in 98% of cases. (Note that this data is presented in a somewhat confusing way in Ref. 10 at p. 15). Against the background of this data it can be readily appreciated that the generally quoted rule of thumb that rigor commences in 6 hours, takes another 6 to become fully established, remains for 12 hours and passes off during the succeeding 12 hours, is quite misleading.

    The intensity of rigor mortis depends upon the decedent's muscular development; consequently, the intensity of rigor should not be confused with its degree of development. In examining a body both the degree (complete, partial, or absent) and distribution of rigor should be assessed after establishing that no artefact has been introduced by previous manipulation of the body by other observers. Attempted flexion of the different joints will indicate the amount and location of rigor.

    As a general rule when the onset of rigor is rapid, then its duration is relatively short. The two main factors which influence the onset and duration of rigor are (a) the environmental temperature, and (b) the degree of muscular activity before death. Onset of rigor is accelerated and its duration shortened when the environmental temperature is high. If the temperature is below 10oC it is said to be exceptional for rigor mortis to develop, but if the environmental temperature is then raised, rigor mortis is said to develop in a normal manner. (Ref. 19 at p. 31). Rigor mortis is rapid in onset and of short duration after prolonged muscular activity, e.g. after exhaustion in battle, and following convulsions. Conversely, a late onset of rigor in many sudden deaths might be explained by the lack of muscular activity immediately prior to death.

    In addition to these two principal factors, other endogenous and environmental factors are claimed to influence the onset of rigor. Onset is relatively more rapid in children and the aged than in muscular young adults. It develops early and passes quickly in deaths from septicaemia or from wasting diseases. It is delayed in asphyxial deaths, notably by hanging or carbon monoxide poisoning, and also when death has been immediately preceded by severe haemorrhage. (Ref. 10 at p. 15).
    […]
     
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  3. BlueCrab

    BlueCrab New Member

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    tipper,

    I agree that is an interesting article. I have personally estimated in the past that full rigor is reached in about 12 hours (with environmental conditions being average) and therefore figured that JonBenet, being in full rigor when found at 1:05 PM on the 26th, likely died around 12 hours sooner, or approximately at 1:00 AM on the 26th.

    However, the above article says the onset of rigor in children is quicker and therefore full rigor is achieved in sooner than 12 hours. But then the article goes on to say that in asphyxia deaths (JonBenet was asphyxiated) the onset of rigor is delayed and therefore takes longer than normal to reach full rigor. It looks like a Mexican standoff; so I guess we should stick to the original standard way of estimating when full rigor occurred in the Ramsey case -- 12 hours.

    BlueCrab
     
  4. tipper

    tipper Former Member

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    I'm not sure I'm comfortable with the 12 hours. I wish he had gone into more detail on the asphyxia information.

    But, as it is, we have asphyxia "notably by hanging or carbon monoxide poisoning" which may cause a delay.

    But we also have her small size, the warmth of the basement and (presumably) muscular activity at time of death and perhaps convulsions from the head blow. All these could offset whatever delay the asphyxia might cause.

    Also, according to the chart 90% of the cases had complete rigor by 9 hours. Why do you think JonBenet would fall into the last +2%?
     
  5. BlueCrab

    BlueCrab New Member

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    tipper,

    She wouldn't. The article said that full rigor had been reached by 12 hours in 98 percent of the cases.
     
  6. aussiesheila

    aussiesheila Inactive

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    Thanks for posting this very interesting article Tipper.

    It shows just how difficult estimating the time of death is based simply on the extent of the rigor.

    So it seems not to be any help to us other than it more or less leaves it open for us to choose any time that fits best with our theory. My choice is 2 am, or immediately after whenever Melody Stanton said she heard the scream.
     
  7. narlacat

    narlacat Former Member

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    maybe not an audible scream but 'rather negative energy radiating from JonBenet' :waitasec:
     
  8. aussiesheila

    aussiesheila Inactive

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    Yeah, maybe
     

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