Friday, December 03, 2010

Explaining The Massei Report: Establishing The Time When Meredith Passed On

Posted by Storm Roberts




Why This Matters So Much

Perhaps the hardest parts of the Massei Report for compassionate readers to take are those concerning Meredith’s wounds and time of death.

Those passages commence early in the report and, as with our translation of much of the Micheli report, left our translators and many readers disturbed and a few of them at least in tears. 

This is an abbreviated overview of how forensic medicine helped the court to establish the time of Meredith’s death.

 

Medical science is often called upon to help to identify a precise time of death.  However, this is not possible.  The only way of knowing a precise time is if the death is witnessed and a time noted - medical science can only give a “time window” during which it is likely that death occurred. 

There are several ways of establishing time of death and I shall look at four, briefly:  the extent of rigor mortis; the temperature of the body;  hypostasis; and, the state of digestion.

Rigor Mortis

Rigor Mortis is the stiffening of muscles after death.  As oxygen is no longer being provided to the tissues of the body certain chemical reactions can no longer happen and changes occur.  In the muscles this leads to a state of contraction which remains until the muscle tissues start to decompose.

Rigor Mortis begins to establish approximately three hours after death and is fully established at twelve hours and remains so until 48 hours.  Rigor then begins to dissipate and 80 - 90 hours after death rigor mortis will have fully dissipated.

Thus rigor mortis can be used to establish an approximate time of death based on the degree of stiffness and whether the body is going into or going out of rigor.  External factors can have an impact on rigor mortis, but as the cause of rigor is a lack of oxygen preventing a chemical reaction taking place external factors have less effect than they do when considering other methods of establishing time of death. 

Body Temperature

The accepted temperature of a healthy human is 37 Celcius.  Upon death the body starts to cool.  The body temperature, normally taken rectally, drops 1-2 Celcius in the first hour and 1 Celcius every hour for the following 8 hours, thereafter the temperature drops gradually until the body reaches ambient temperature.

Factors that can affect this process, thus complicating it’s application to the establishment of the time of death include:

- the covering of the body as this insulates and changes the rate at which the body loses heat;
- injuries sustained and blood loss; and,
- any change in the environmental temperature (if the temperature surrounding the body changes - such as a night time temperature drop or if the body is moved).

Hypostasis.

Hypostasis is the settling of red blood cells under the force of gravity - the red blood cells fill capillaries (our smallest blood vessels) giving a red coloration to the skin.  Initially the red blood cells are still mobile however eventually they coagulate and the coloration becomes fixed.  It is generally accepted that the coloration (stain) appears one to two hours after death and begins to fix, from the central area of the stain outwards, from around the sixth to eighth hour.  Fixation is complete from 24 to 36 hours after death.

Stage of digestion.

From the time we start to eat a meal, and thus initiate the digestion process in the stomach, there is a set pattern of events within the digestive process that can allow us to determine approximately how long after the start of the last meal digestion was interrupted by death.

When we eat a meal our food is initially broken down my two main means: firstly - chemical, namely enzymes and the acid in our stomach; and, secondly - mechanical, namely chewing and the action of the stomach muscles.  Once our food has achieved a liquid consistency it is able to leave the stomach and enter the first part of our intestines - the duodenum.

This emptying of the stomach normally occurs from around 3 hours after eating.  However, how fast we digest a meal and the stomach empties depends on a multitude of factors, just a few of which are:

  • what we have eaten;
  • how the food was prepared;
  • how our body reacts to the food;
  • our state of mind (for example: ever had “butterflies” or an upset stomach when you were worried or excited? );
  • our state of health; and,
  • what we drank with our meal.

In reality the speed of digestion varies not only person to person but meal to meal - You could eat the same meal twice and have significant differences in the speed of digestion each time.

If our “fight or flight” mechanism - the release of adrenaline - is bought into play it is possible for the digestive process to temporarily halt as our body diverts it’s resources to deal with more pressing matters of survival.  This however is not certain, everyone is different and how such things affect us is unique.

What is explained in the report

Above I said that the stomach can empty after 3 hours, all of the above factors and many more can more than double that time to 6 hours or possibly more.  Professor Cingolani testified that the stomach can empty after as little as one hour or take as long as 12 or more hours.  Thus as stated above, the state of digestion, whether the stomach has emptied or not, is only able to provide a “time window” during which death could have occurred.

N.B.  The following references to page numbers relate to the translation of the Massei Report (see link in the menu to the left of your screen) - specifically the first published version - v1.0 - dated 8th August 2010.

The Massei Report [Page 109 (full medical forensic considerations) and Page 173(specific report on the time of death.)]

The first thing the Massei Report notes on the subject of determining the time of death is that all the expert witnesses emphasised how difficult it is to determine, in part because there are “variables which are not always determinable and measurable with the necessary precision.”

The experts heard by the court on this matter were:

  • The Coroner, Dr. Lalli (whose evidence with regards to his observations and calculations regarding time of death are on Pages 113 to 116 of the Massei Report);
  • Consultant appointed by the Public Ministers (prosecution), namely Professor Mauro Bacci;
  • Consultants appointed by the court (the GIP - judge at a previous hearing), namely Professor Giancarlo Umani Ronchi and Professor Mario Cingolani;
  • Consultant for the civil party, namely Professor Gianaristide Norelli;
  • Consultant for the defence of Amanda Knox, namely Professor Carlo Torre; and,
  • Consultants for the defence of Raffaele Sollecito, namely Professor Francesco Introna and Professor Vinci.

Evidence such as the time of Meredith’s last meal (approximately 18.30 hrs) and when she was last seen by her friends (a few minutes before 21.00 hrs) was used by the court to ascertain the earliest possible time of death, i.e. 21.00 hrs was the last time Meredith was seen alive and the “time window” calculated with reference to forensic medical evidence could not start earlier than that [Page 131].

Arguments were heard with regards to how various factors would have affected calculation of time of death, these are all detailed in the Massei Report as are the different views and opinions of the various consultants noted above.  The main points of contention were the effect the covering of the body had and the timing of the emptying of the stomach. 

Details from the report

Dr. Lalli saw the body at around 14.40 to 15.00 hrs on 2nd November and noted that there was “cadaveric rigidity… of the ankle and toes”  [Page 110].  He did not examine the body fully at that time as the scientific police were conducting their investigation and it was important to preserve the crime scene so they could do their job.  He first examined the body at 00.50hrs on 3rd November 2007 - it was subject to rigor mortis.  Rigor was still established at 12.00 hrs on 3rd November and was resolved by 10.00 hrs on 4th November - and thus he considered that the stages of rigor supported the time window established by the temperature of the body.

Dr. Lalli used both his experience of various factors which affect the rate of loss of heat energy from the body and also mathematical methods - namely the application of the Henssge nomogram - to establish a time window by considering the body temperature. 

His calculations led to him reporting a window of between 21 and a half hours and 30 and a half hours prior to his first examination of the body (00.50 hrs 3rd November).  He noted that the intermediate point of this window was 23.00 hrs on 1st November [Page 173]. Discussions centred on the weight of the body and also the effect of the cover placed over the body specifically how these would effect the application of the Henssge nomogram.

Looking at the hypostatic staining in this case did not help to narrow the time window [Page 114].  During his first examination of the body at 00.50 hrs on 3rd November Dr. Lalli noted that the stains were not fully fixed - digital pressure caused the stain to fade but not to disappear.  In the following examination at 12.00 hrs on 3rd November the hypostasis was “fixed to finger pressure”. 

This indicated that death occurred 24 to 36 hours earlier - however it is not known at what precise point in time between the first and second examination of the body that fixation occurred - therefore the court considered that the time of 12.00 hrs on 3rd of November was the latest possible time to count back the 24 to 36 hours.

Iin other words based on the observations and the times they were made the time window suggests death was between 24.00 hrs on 1st November and 12.00 hrs on 2nd November however full fixation of the stains occurred at a point between 00.50 hrs and 12.00 hrs on 3rd November if that point in time were known it would allow the time window to be pushed back and be more accurate.  As this was not possible the court concluded that hypostasis was unable to provide information more accurate than that provided by the temperature of the body.

With regards to the state of digestion discussions covered areas included the time of the meal Meredith had shared with her friends (around 18.30 hrs), the point from which calculations should be taken, what had been eaten and the degree of digestion and how long it would take for the stomach to empty. 

Also discussed was the possibility that Meredith might have had a snack when she returned to her home, a snack which might have included mushroom and a small quantity of alcohol (no more than a small glass of beer or wine) - it is not certain that she partook of such a snack but it was considered by the court [Page 179]. 

Dr. Lalli concluded that the time of death suggested by the state of digestion would have been between 21.00 hrs and 24.00 hrs on 1st November [Page 174] which is consistent with the time of death suggested by the temperature of the body and rigor.  However other consultants, particularly those appointed by the GIP emphasised that this method has many variables and thus cannot provide an accurate time window [Page 179].

Conclusion.

The time of death can be said to be within a ten hour time window of between 18.50 hrs on 1st November and 04.50 hrs on 2nd November.  The court and all the consultants and experts agreed on this time window [Page 179].  The mid point of this window is 23.50 hrs on 1st November.  Meredith was last seen alive by her friends at 21.00 hrs on 1st November 2007.

However, forensic medical evidence is only one aspect of this case.  Evidence with regards to biological trace evidence, telephones, computers and witness statements, for example were also introduced to the court and are detailed in the Massei Report.  After careful consideration and weighing of all the facts the court concluded that Rudy Guede, Amanda Knox and Raffaele Sollecito entered the house at 7 Via della Pergola at around 23.00 hrs [Page 361] and Meredith was murdered shortly after 23.30 on 1st November 2007 [Page 382].




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