A distinction-grade assignment on the time of death and how taphonomy and entomology can aid in the process of determining the time of death. Well laid out, and easy to read.
Time of Death (TOD) is the estimation of the time a body had died. There is also a formula we can
use to calculate it. The formula is: Time since death= (98.6- body temperature)/T. Time since death
is measured in hours, body temperature is in Fahrenheit and T depends on the ambient
temperature. T is a variable because the body starts to cool down, right after it dies, and depending
on the ambient temperature, this process will be sped up or slowed down. 32°F is the threshold for
this as, this is the temperature at which water freezes, and if a body died when the ambient
temperature was below this, the body would cool down quicker, but it would also experience
delayed decomposition.
Example calculation 1:
Time since death= (98.6- body temperature)/T = (98.6-62.6)/0.75 =48 hours
Example calculation 2:
Time since death= (98.6- body temperature)/T = (98.6-28.4)/1.5 =46.8 hours
Total body score (TBS)
Total Body Score (TBS) is the average of how different parts of the body have decomposed. It mainly
focuses on the head, torso and limbs, as they are the biggest parts of the body which take the
longest to decompose. The head takes the longest to decompose. This is because the bugs have to
break through the membrane through the nose to get to the skull and the brain which is the thickest
membrane in the body for the bugs to eat through. This average is then used in conjunction with the
Accumulative Degree Days to help determine the TOD more accurately. TBS is calculated using a
point-based system, where the different degrees of decomposition of each of the parts of the body
gets a certain number of points, and then each number of points is added together.
Accumulative Degree days (ADDs)
Accumulative Degree Days (ADDs) are how much the temperature has changed in the days since the
TOD. It is the average ambient temperature, but with the basal (base) body temperature subtracted.
(The lowest temperature of the body, which may be at the time of calculation, but not always). This
is calculated using: (Maximum ambient temperature + minimum ambient temperature)/2- base
body temp. This is most used in combination with TBS as the TBS can be involved in a different
calculation for ADDs. There are also Accumulative Degree Hours (ADHs) which is how much the
temperature has changed in the hours since TOD.
Minimum Post-mortem interval (Minimum PMI)
There is no minimum PMI when it comes to the body itself. There is a 75-year rule which means that
after 75 years, not a lot of evidence can be gained from the bones of the body at that point.
However, there is an estimation of the amount of time a body has been dead that is based off the
assumption that the bugs associated with decomposition arrive at the body immediately after the
body dies. This is also called the Minimum PMI, more commonly written like PMImin. (A Wilson, 2019,
online)
, Taphonomy Techniques
There are taphonomy techniques that can be used to determine time of death (TOD), each of these
have different ways to help determine TOD. For example, the appearance of the body uses the
stages of death, stages of decomposition and insect activity to determine the TOD. Whereas the
environment around the body and the temperature of the body use temperature to estimate the
TOD. These different techniques change depending on the stage of decomposition the body is at and
what stage of mortis the body is at.
Appearance of the body
First stage of decomposition
The appearance of the body can help determine TOD because as the body goes through the different
stages of decomposition, the appearance of the body changes. For example, in the first stage of
decomposition (which happens in the first 24-72 hours after death) the autolysis of the body begins
(where the body’s cells break down automatically) and a small number of flies and larvae will be
present. This is because the putrefaction that attracts the bugs has not yet been released. As there
will not be many changes to the body’s appearance, this means that if you can across a body with a
similar appearance to its normal state, you would know it had only been dead for between 24-72
hours.
Stage 2 of decomposition
In the second stage of decomposition where the body begins to bloat, this happens 2-6 days after
death. This means that bodies in the second stage of decomposition will appear with more holes in
the skin where the bugs have begun to eat away at the body, while also being more bloated.
However, this means that the bloating begins to subside as the bugs begin to eat the body. So, if you
see a bloated body or a body where the bugs have begun to eat away at it, it means that the body
has been dead for between 2-6 days, this would be the TOD estimate.
Stage 3 of decomposition
A body in the active decay stage of decomposition, will appear with more skin damage and organ
damage due to the bugs present, there will also be bugs at many stages of their life cycle present at
this stage. This active decay stage happens at around 7-11 days after death, this is where the body
forms blisters due to the gas release and the putrefaction formed also begins to leak from the body.
When you find a body which has leaked the putrefaction and has blisters, you would know that it has
been dead for between 7-11 days.
Stage 4 of decomposition
In the post decay stage of decomposition, the body will appear with open cavities in the chest and in
other areas, this is because by this point the bugs have eaten almost everything they can of a body,
leaving only the bones, teeth and hair behind. At this stage there would also be dead bugs on the
body. If you came across a body with parts of its skin missing as well as dead flies and pupae near it,
you’d know that the body was dead 10-24 days as the post decay stage of decomposition does not
start until this time frame.
Final stage of decomposition
In the final stage of decomposition, known as the dry stage, the body would now just be bones,
there would be no skin left at all, making the body hard to identify unless dental records are used. If
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