Time of Death Estimation

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Time of Death Estimation
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Quotes say it all

• http//www.dundee.ac.uk/forensicmedicine/llb/timed
  eath.htm
• "No problem in forensic medicine has been
  investigated as thoroughly as that of determining
  the time of death on the basis of post mortem
  findings. Apart from its obvious legal
  importance, its solution has been so elusive as
  to provide a constant intellectual challenge to
  workers in many sciences. In spite of the great
  effort and ingenuity expended, the results have
  been meagre". (Ref. 15 at p. 33.)

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Quotes say it all

• "Whatever method is used to calculate the
  estimated time since death from body temperature,
  all the variable factors must be taken into
  account to modify any basic formula, though this
  adjustment is very arbitrary and can only be
  attempted in the light of previous experience.
  When a "favoured" time of death is decided upon
  this should never be offered to the investigating
  authorities as a single point in time. It must be
  used to construct a "bracket of probability",
  giving an earliest and latest time between which
  the doctor feels that death must have occurred.
  The width of this time bracket will depend upon
  the number and uncertainty of the variable
  factors known to the doctor and is likely to be
  longer the more remote the death was from the
  time of examination of the corpse. It is futile
  mentioning any time in units of less than an
  hour, even when the death was quite recent. A
  medical witness who attempts to determine the
  time of death from temperature estimation in
  minutes or fractions of hours is exposing himself
  to a severe challenge to his expertise which may
  well amount to near ridicule, thus denegrating
  the rest of his evidence". (Ref. 10 at p. 12.)

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Quotes say it all

• "The timing of the sequence of events concerned
  in the dissolution of the body cannot be done
  with accuracy and one must be cautious never to
  pronounce too readily that the decomposed state
  of the body is inconsistent with the time
  interval alleged". (Ref. 6 at p. 91.)

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Sources of Evidence

• Evidence for estimating the time of death may
  come from three sources
• Corporal evidence, i.e. that present in the body.
  
• Environmental and associated evidence, i.e. that
  present in the vicinity of the body,
• Anamnestic evidence, i.e. that based on the
  deceased's ordinary habits, movements, and day to
  day activities.
• All three sources of evidence should be explored
  and assessed before offering an opinion on when
  death or a fatal injury occurred.

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Two Methods for Estimating TOD

• The rate method. Measuring the change produced by
  a process which takes place at a known rate which
  was either initiated or stopped by the event
  under investigation, i.e. death. Examples include
  the amount and distribution of rigor mortis, the
  change in body temperature, and the degree of
  putrefaction of the body.
• The concurrence method. Comparing the occurrence
  of events which took place at known times with
  the time of occurrence of the event under
  investigation, i.e. death. For example, a wrist
  watch stopped by a blow during an assault, the
  extent of digestion of the last known meal.

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Things Affecting Algor Mortis

• Size of Body - surface to mass ratio children
  lose heat faster (larger surface to mass ratio)
• Clothing on body
• Immersion in water water is a better conductor
  of heat
• Movement and humidity of air wind increases
  cooling humidity increases cooling

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Time and Rigor Mortis
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Factors affecting rigor mortis

• 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 artifact 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.

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Rigor mortis facts

• Early onset means short duration
• Muscular activity increases early onset
• Higher environmental factors increases onset and
  decreases duration
• Freezing can stop rigor mortis. Once thawing is
  complete, rigor mortis can begin
• Cadaver spasm extreme event at time of death
  creates muscle contraction immediately at time of
  death and lasts into rigor mortis

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Factors affecting livor mortis

• The process begins immediately after the
  circulation stops, and in a person dying slowly
  with circulatory failure, it may be pronounced
  very shortly after death. Lividity is present in
  all bodies, although it may be inconspicuous in
  some and thus escape notice.

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VITREOUS HUMOUR POTASSIUM

• Up to 100 hours post mortem, the 95 confidence
  limits of different authors vary between 9.5
  hours up to 40 hours
• In the early post mortem interval up to 24 hours,
  the 95 confidence limits of different authors
  varies from 6 hours up to 12 hours.
• There are also sampling problems in that the
  potassium concentration may differ significantly
  between the left and right eye at the same moment
  in time.

13
Forensic Entomology

• First to arrive Diptera, in particular the blow
  flies or Calliphoridae and the flesh flies or
  Sarcophagidae
• The females will lay their eggs on the body,
  especially around the natural orifices such as
  the nose, eyes, ears etc

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Some development data on different species of
blowflies (Calliphoridae) and fleshflies
(Sarcophagidae)
Life histories of 11 species of blowflies and
fleshflies reared at 27 degrees Celsius, and 50
percent relative humidity First Second Third
Total No. of Egg instar instar
instar Prepupa Pupa Immature Gen.
(Hrs) (Hrs) (Hrs) (Hrs) (Hrs) (Days) (Days)
Sarcophaga cooley 29 -- 24 18 48 96 9
16 Sarcophaga shermani 28 -- 22 16
48 104 8 14 Sarcophaga bullata 18 -- 26 18
54 112 12 17 Phormia regina 23 16 18
11 36 84 6 11 Protophormia terranovae
27 15 17 11 34 80 6 11 Lucilia sericata
29 18 20 12 40 90 7 12 Eucalliphora
lilaea 27 22 22 14 36 92 6 13
Cynomyopsis cadaverina 17 19 20 16 72 96
9 18 Calliphora vomitoria 5 26 24 48 60
360 14 23 Calliphora vicina 5 24 24
20 48 128 11 18 Calliphora terranovae
4 25 28 22 44 144 12 20 (After Kamal,
1958)
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• http//folk.uio.no/mostarke/forens_ent/tables_deve
  lopment.html

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http//folk.uio.no/mostarke/blowflydev.gif
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• One important biological phenomenon that occurs
  on cadavers are a succession of organisms that
  thrive on the different parts. E.g. beetles that
  specialize on bone, will have to wait until bone
  is exposed. Predatory rove beetles or parasites
  that feed on maggots will have to wait until the
  blow flies arrive and lay their eggs.
• The succession on cadavers happens in a fairly
  predictable sequence and can be used in
  estimating time of death if the body has been
  lying around for some time. Here is a table over
  a succession experiment on guinea pigs performed
  by Bornemizza in 1957
• http//folk.uio.no/mostarke/forens_ent/successiont
  able.html

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• Case No. 1
• On 4 June the partially clad body of a young
  female was found alongside a rural highway in the
  northwestern United States. An autopsy revealed
  that she had died of multiple head and neck
  wounds inflicted by a heavy sharp object. She was
  subsequently identified as a 14-year old
  prostitute. Her brother reported her as missing
  approximately four days prior to discovery of her
  corpse.
• She had last been seen alive on the morning of 31
  May in the company of a 30-year old army
  sergeant, the primary suspect. While considerable
  circumstantial evidence supported the theory that
  the victim had been murdered by the sergeant, an
  accurate estimation of time of death was crucial
  to establishing a possible link between the
  suspect and the victim at the time when death
  occurred.

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Case 1

• Several estimates of postmortem interval were
  offered by medical examiners and investigators.
  These were based largely on the physical
  appearance of the body and the extent to which
  decompositional changes had occurred in various
  organs. They were not based on any quantitative
  scientific methodology.
• Numerous fly larvae (maggots), adult flies, and
  other insects were observed and collected in and
  around the victim's wounds. Some were placed
  alive in small containers and subsequently reared
  to produce adult flies. Others were placed
  immediately into a liquid preservative.
  Additional specimens collected at the autopsy
  were processed in a similar manner. Numerous
  photographs of the crime scene, the surrounding
  vegetation and terrain, and the corpse were
  taken. These photographs included enlargements
  illustrating the adult flies and maggots present
  at the time the body was discovered

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Case 1

• Reports describing the condition of the body when
  found and detailing autopsy procedures and
  results also were reviewed. Climatological data,
  including maximum and minimum temperatures,
  incidence of rainfall, cloud cover, wind speed
  and direction, and relative humidity, were
  obtained from a government weather station
  located a short distance from where the victim
  was found. These data indicated the environmental
  conditions to which the remains and its insect
  associates were exposed.
• Based on this total array of evidence,
  entomologists determined that the first insects
  to colonize the remains had arrived on 31 may.
  The insect evidence indicated a PMI of four days.

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Case 1

• Based on this evidence, the army sergeant with
  whom the victim had been last seen alive was
  arrested and charged with first degree murder. On
  questioning he admitted to having murdered the
  victim by striking her six to eight times with a
  small hatchet sometime around noon on May 31.
  Subsequently, he entered a plea of guilty to the
  murder charge and was sentenced to life in prison
  without parole.

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Case 2

• Recently, in New England, the fully-clothed body
  of a young adult woman was found in a parking lot
  located behind an urban industrial complex. The
  victim had died from a single, 9mm bullet wound
  to the right temple, and a substantial pooling of
  blood was noted beneath the victim's head. The
  body was discovered initially by employees
  reporting for work at approximately 600 a.m. No
  insect evidence was observed on or around the
  body during the preliminary crime scene survey.
  As the investigation proceeded, however, and the
  body was warmed by the morning sun, small numbers
  of green bottle flies (Phaenicia sericata) were
  observed feeding at the bullet wound. By the time
  the corpse was removed from the scene, patches of
  eggs were present in and around the wound.
  Knowing that the previous day's climatic
  conditions were ideal for blow fly activity, that
  adult blow flies are not typically active at
  night, and that blow flies would be highly
  attracted to the pooled blood, entomologists
  concluded that the victim had been killed during
  the hours of darkness preceding the discovery of
  the body. It was later determined that the young
  woman had been last seen alive around midnight of
  the previous day.

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Case 3

• The remains of a murder victim were reportedly
  thrown down an open well on a small farm in a
  rural area in south-central Indiana. Then the
  well was completely filled with junk, tires, and
  rocks. The exact location of the well where the
  remains were deposited was unknown, but as the
  investigators drove into one of several wooded
  farm yard sites being investigated, it was
  obvious they had found the right location.
  Several thousand flies were hovering over a pile
  of old tires. The remains were found at the
  bottom of the well under the debris.
  Decomposition was advancing in the body, but
  there were no insects found on it. Access to the
  body by the blow flies was prevented by the
  intervening material, but odors were still
  capable of attracting multitudes of insects.

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Case 4

• On a midmorning in August, the half-nude body of
  a young female was discovered, more or less face
  down, among a group of junk automobiles near
  Spokane, Washington. The victim had died of
  multiple stab wounds to the chest and neck, and
  adult blow flies were observed in and around the
  wounds. Blow fly eggs were collected from the
  wounds at autopsy in the late afternoon.
  Subsequent dissection of the eggs showed no
  embryonic development suggesting that they had
  been deposited on the remains less than eight
  hours earlier.

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Case 4

• The victim had been last seen alive during the
  evening two days prior to her discovery. The
  insect evidence, however, suggested that the
  young woman had been murdered during the hours of
  darkness preceding the finding of her remains.
  Had the victim died any earlier, young fly larvae
  (maggots) rather than eggs would have been
  collected from her wounds. Climatic conditions on
  both days prior to her discovery were suitable
  for adult blow fly activity and egg laying. A
  subsequent investigation verified these findings,
  revealing that the victim had been murdered
  during the hours of darkness just prior to the
  morning of her discovery.

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Case 5

• In early Spring, the fully-clothed body of a
  young, white male was found in a sandy, shrub
  habitat, in the southwestern United States. The
  victim had died of multiple small caliber bullet
  wounds to the chest and back. There was little
  external evidence of decomposition. A small
  amount of blood was observed to have oozed from
  the victim's left nostril, partially coating his
  left eye.
• A small irregular granular mass was collected
  from the surface of the victims left eye. Closer
  examination of this substance revealed it to be a
  small mass of blow fly eggs. Several eggs had
  hatched already.

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Case 5

• These maggots were reared to adults and were
  subsequently identified as Cochliomyia
  macellaria, the secondary screw worm. Based on
  the climatic conditions and knowledge of the
  developmental biology of this fly, it was
  determined that the eggs most likely had been
  laid on the corpse 24 to 36 hours prior to the
  time the corpse was found. Subsequent
  investigation determined the identity of the
  victim. He had last been seen alive in the
  company of a male companion approximately 36
  hours prior to the time his corpse was found. It
  was later determined that the victim had been
  murdered by his companion approximately 36 hours
  prior to discovery of the remains.

http//www.research.missouri.edu/entomology/casest
udies.html