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FEATURE ARTICLE
KALPANA
ALPANA SINGH AND RE
EEMA
EMA SO
ONKER
Forensic entomology does not only help in conviction but has
also helped in saving lives.
‘Who saw him die, I, said the fly, with my
little eyes, I saw him die’.
I
N 1999, two bear cubs were found
shot, disembowelled, with their gall
bladders removed in Manitoba, Canada.
Two suspects were caught but there was
no evidence against them.
Conservation Officers along with
a Royal Canadian Mounted Police
(R.C.M.P.) examining the scene of crime
collected adult blow flies coming to lay
eggs and the blow fly eggs themselves
from the remains. The maggots hatching
from eggs were reared to adulthood. The
hatching time, climatic conditions and lab
data were used to ascertain the time of
death. This time was consistent with the
time that the defendants were seen at the
scene of crime. The evidence was used in
their conviction.
Insect evidence has been routinely
analysed to arrive at convictions in
homicide cases as well as poaching cases.
Forensic entomology applies the study
of insects and other arthropods to legal
cases, especially in a court of law.
These applications are wide ranging
but the most frequent is determining the
post mortem interval (PMI) in suspicious
death investigations. Here the insect and
its stage found on the corpse are analysed
and used for precise estimation when the
SCIENCE REPORTER, JULY 2015
Many insects are attracted to a dead and decaying body depending upon its stage of decomposition
(Source: http://www.sfu.museum/forensics/eng/pg_media-media_pg/entomologie-entomology/photo/206/)
pathological reports have given a broad
approximation.
soft drinks, flies in ketchup, beetle legs,
body parts found in chocolates etc.).
Categories of Forensic
Entomology
• Medico-criminal entomology deals
with arthropod involvement in usually
violent crimes such as murder, suicide
and contraband trafficking.
Forensic entomology can be of four
major kinds: urban, stored products,
medico-legal or more appropriately
medico-criminal, and wildlife forensic
entomology.
• Urban forensic entomology deals with
law suits about misuse of pesticides and
litigations and civic law actions involving
arthropod pests in house or garden.
• Stored product forensic entomology
generally deals with litigations and civic
law suits involving arthropod infestation
or contamination of a wide range of
commercial products (insects found in
20
• Wildlife forensic entomology helps in
settling cases related to wildlife crimes
such as poaching and trafficking.
History of Forensic Entomology
The first documented case of the use of
forensic entomology in solving a crime
is found in a 13th century medico-legal
Chinese textbook by Sung Tzu named ‘Hsi
Yuan Chi Lu’ (one possible translation
‘The Washing Away of Wrongs’). It
describes a stabbing near a rice field. The
investigator tells all workers to lay down
FEATURE ARTICLE
Not only presence but absence of particular
insects is also an important clue
Forensic entomology as a
science is yet to find its place
in legal proceedings in our
county. Under Article 138 of
the Evidence Act of the Indian
Constitution any scientific
evidence is allowed before
court of justice to prove a case.
Thus, a general awareness
about this branch of science
is required as well as trained
forensic entomologists.
shows evidence of early and active
infestation it means this is an antemortem
wound. Colonization pattern of insects
on antemortem and postmortem wounds
leads to variation in the decomposition
process. Defensive wounds also show
abnormal colonization of insects. Hence,
the amount of insects inside the body can
reveal the mode of death.
their sickles before him. The flies attracted
by invisible traces of blood hover around
one sickle only indicating the culprit who
had washed the blood from his sickle.
The rst case reported to estimate
the post-mortem interval (PMI) was by
a French physician Bergeret in 1855. The
case involved blow fly pupa and larval
moths. Though a doctor in a hospital, he
observed that the state of the corpse was
similar to a few other found in different
locations on the basis of entomological
evidences.
In 1881, a German medical doctor
Reinhard reported the rst systematic
study of forensic entomology when
he involved Brauer an entomologist of
Vienna, to identify some phorid flies
found on exhumed bodies in Saxonia. He
also gave a description of beetles from
graves older than 15 years.
Around the same time an army
veterinarian
Jean
Pierre
Megnin
documented his work on insects of
forensic importance in two volumes
– Faune Des Toumbeaux (Fauna of the
Tombs, 1887) and La Faune Des Cadavers
(Fauna of the Corpses, 1894). Megnin’s
work not only advanced the eld of
forensic entomology but also greatly
popularized the subject.
Applications of Forensic
Entomology
There have been cases involving
entomological evidences that demonstrate
evidence may still be found after months
or after renovation of a flat in which
necrophagous (corpse eating) blow fly
larva fell from a corpse, hid and developed
after months even after disinfection. In a
case where even autopsy could not reveal
the cause of death, insects developed on
the corpses were found containing certain
toxic chemicals. Thus, the cause was
found to be death by poison.
Some insect species are speci c in
terms of locations so they are used to
determine the geographical location of the
occurrence of a crime despite a different
site of disposal of the body.
A forensic entomologist can easily
distinguish which wounds occurred
before or after the victim’s death. In a
live person scratches, stab wounds or
injury by bullet will bleed. Since insects
have very speci c food preferences, fresh
blood attracts those necrophagus species
that feed on this meal. They feed and lay
eggs in these open wounds. Postmortem
wounds tend not to bleed so will be dry
and clean and much less insects will be
attracted to this feeding site. If a wound
21
Sometimes insects’ blood trails,
feces, eggs and larvae play an important
role in determination of the time of the
crime. Not only presence but seldom
absence of the particular insects indicates
an important clue about the crime scene.
Many types of insects are studied in
forensic entomology ranging from flies,
cockroaches to necrophagous insects.
Nechrophagous insects such as blow
flies, flesh flies, cof n flies, corpse flies,
scavenger flies, certain beetles, mites,
moths, ants, bees etc. are particularly
relevant to medico-criminal forensic
entomology.
Stages of Dead Body
A dead body, either of a human or
an animal, undergoes many changes
caused by autolysis of tissues. Postmortem changes may be categorised
into at least the following ve stages viz.
Early stage (0-2 hours), Late stage (2-4
hours), Putrid tissue changes stage (4-48
hours), Bloated stage (48-96 hours), and
skeleton destruction stage (days-months).
Many insects are attracted to a dead and
decaying body depending upon its stage
of decomposition. This is called faunal
succession. Faunal succession is affected
by a number of factors such as weather,
sun exposure, air exposure, moisture
level, geography, etc.
SCIENCE REPORTER, JULY 2015
FEATURE ARTICLE
Many types of insects are studied in forensic entomology ranging from flies, cockroaches to necrophagous insects
Techniques in Forensic
Entomology
During most of the history of forensic
entomology taxonomic identification
based on morphology has been a muchused technique. Potassium permanganate
staining of eggs and mock crime scene
creation using dead animal in place of
corpse to study species succession are
other techniques used. Larval weight,
larval length and accumulated degree
hour techniques are popularly used to
assess PMI.
Nowadays with the advent of more
sophisticated tools such as SEM (Scanning
Electron Microscope) and techniques
such as molecular genotyping based
on both mitochondrial DNA as well as
nuclear DNA and gene expression studies
the study of entomological evidences has
become faster and more precise. Insect
characterisation may also be done on the
basis of their allozymes.
Cases Cracked
In UK, Blowfly larvae were discovered
on decaying human remains dumped in
a small ravine in Dumfriesshire, Scotland,
in September 1935. The remains were
later recognized as those of the wife and
maid of Dr. Buck Ruxton of Lancaster. Dr
A.G. Mearns reared the maggots in the
laboratory and provided a vital clue as to
when the murders took place. It helped
prosecutors to find Dr. Ruxton guilty of
the murders leading to his execution.
SCIENCE REPORTER, JULY 2015
Some insect species are specific in terms of locations so they are
used to determine the geographical location of the occurrence of a
crime despite a different site of disposal of the body.
In Germany in 1948, a body of a dead
woman wrapped in a sack was found in
a moat of a mill. The body was naked
except for a pair of red socks. The question
was whether the body was dumped
immediately after killing or whether it
was stored somewhere else before being
dumped there. A caddis fly casing was
found on one sock and was sent to Hubert
Caspers from the Zoological Institute and
Museum of the state of Hamburg. The red
fibres of the sock could be clearly seen on
the upper and lower region of the case,
meaning that the case was already built
before entering the sack and since the
attachment process takes about several
days it was estimated that the body was
somewhere else. Later on it was dumped
in the moat after at least a weak.
Forensic entomology does not only
help in conviction but has also helped in
saving lives. In Austria once there was
a case in which a father was thought to
have killed his three-year-old child by
making her drink sulphuric acid. The
father however stated that he had put the
child after it had died of natural causes
near the window as it was night. In the
morning the child’s head was found to be
covered with ants. A medical examiner’s
findings at autopsy were consistent
with the father’s statement thus saving
his life.
22
Future Furore
Despite 150 years of usage mostly in
Europe and USA forensic entomology
is still a young discipline especially in
India. It is an important branch of science
that helps in estimating not only PMI, but
also whereabouts of dead bodies. It also
helps in estimating drugs and toxicants
ingested by a person when alive and also
of possible post-mortem manipulations.
It may even help in cases of neglect of
people who are alive but in need of care
by estimating the presence of certain
insects or their stages on wounds and
natural orifices.
Forensic entomology as a science is
yet to find its place in legal proceedings
in our county. Under Article 138 of the
Evidence Act of the Indian Constitution
any scientific evidence is allowed before
the court of justice to prove a case. Thus,
a general awareness about this branch
of science is required as well as trained
forensic entomologists. In wildlife cases
many conservation officers are also
unaware of this field of science.
Dr. Kalpana Singh is an Assistant Professor in
Department of Zoology, University of Lucknow,
Lucknow-226007; Email: [email protected]
com.
Reema Sonker is a research scholar in the same
department.