Alan Gunn – Essential Forensic Biology (2006)

Автор: Alan Gunn
Название книги: Essential Forensic Biology (2006)
Формат: PDF
Жанр: Биология
Страницы: 305
Качество: Изначально компьютерное, E-book

The word ‘forensic’ derives from the Latin forum meaning ‘a market place’: in
Roman times this was where business transactions and some legal proceedings
were conducted. For many years the term ‘forensic’ had a restricted definition
and denoted a legal investigation but it is now commonly used for any detailed
analysis of past events, i.e. when one looks for evidence. For example, tracing the
source of a pollution incident is now sometimes referred to as a ‘forensic envi-
ronmental analysis’, determining past planetary configurations is referred to as
‘forensic astronomy’, whilst historians are said to examine documents in ‘foren-
sic detail’. For the purposes of this book, ‘forensic biology’ is defined broadly as
‘the application of the science of biology to legal investigations’ and therefore
covers human anatomy and physiology, organisms ranging from viruses to ver-
tebrates and topics from murder to the trade in protected plant species.
Although forensic medicine and forensic science only became specialized areas
of study within the last 200 or so years, their origins can be traced back to the
earliest civilizations. The first person in recorded history to have medico-legal
responsibilities was Imhotep, Grand Vizier, Chief Justice, architect and personal
physician to the Egyptian pharaoh Zozer (or Djoser). Zozer reigned during
2668–2649 BC and charged Imhotep with investigating deaths that occurred
under suspicious circumstances. The codification of laws was begun by the
Sumerian king Ur-Nammu (ca. 2060 BC) with the eponymous ‘Ur-Nammu Code’
in which the penalties of various crimes were stipulated whilst the first record
of a murder trial appears on clay tablets inscribed in 1850 BC at the Babylonian
city of Nippur. The word ‘murder’ probably derives from the Old English
‘morder’ or ‘morther’ (verb = mortheren) whilst homicide is derived from the
Latin ‘homo’, a man, and ‘caedere’ meaning to strike, cut or kill. A homicide
may be either a murder, if malice was involved, or a consequence of manslaugh-
ter if it occurred as an accident or during self-defence. Although the ancient
Greeks are known to have performed human dissections, Julius Caesar (102/100
– 44 BC) has the dubious distinction of being the first recorded murder victim
in history to have undergone an autopsy. After being assassinated, his body was
examined by the physician Antistius who concluded that although Julius Caesar
had been stabbed 23 times only the second of these blows, struck between the
first and second ribs, was fatal.
In England, the office of Coroner dates back to the era of Alfred the Great
(871–899) although his precise functions at this time are not known. It was
during the reign of Richard I (1189–1199) that the Coroner became an estab-
lished figure in the legal system. The early Coroners had widespread powers and
responsibilities that included the investigation of crimes ranging from burglary
to cases of murder and suspicious death. The body of anyone dying unexpect-
edly had to be preserved for inspection by the Coroner, even if the circumstances
were not suspicious. Failure to do so meant that those responsible for the body
would be fined, even though it might have putrefied and created a noisome
stench by the time he arrived. It was therefore not unusual for unwanted bodies
to be dragged away at night to become another village’s problem. The Coroner’s
responsibilities have changed considerably over the centuries but up until 1980
he was still expected to view the body of anyone dying in suspicious circum-
stances. Although the Coroner was required to observe the corpse he did not
undertake an autopsy. In European countries, the dissection of the human body
was considered sinful and was banned or permitted only in exceptional cir-
cumstances until the nineteenth century. Most Christians believed that the body
had to be buried whole otherwise the chances of material resurrection on Judge-
ment Day were slight. The first authorized human dissections took place in 1240
when the Holy Roman Emperor Frederick II decreed that a corpse could be dis-
sected at the University of Naples every five years to provide teaching material
for medical students. Subsequently, other countries followed suit, albeit slowly.
In 1540, King Henry VIII became the first English monarch to legislate for the
provision of human dissections by allowing the Company of Barber Surgeons
the corpses of four dead felons per annum, and in 1663 King James II increased
this figure to six per annum. Subsequently, after passing the death sentence,
judges were given the option of permitting the body of a convicted criminal to
be buried (albeit without ceremony) or to be exposed on a gibbet or dissected.
Nevertheless, the lack of bodies and an eager market among medical colleges
created the trade of body snatching. Body snatchers were usually careful to leave
behind the coffin and the burial shroud because taking these would count as a
felony (i.e. a serious criminal offence), which was potentially punishable by
hanging. Removing a body from its grave was classed as merely a misde-
meanour. The modern-day equivalent is the Internet market in human bones of
uncertain provenance (Huxley and Finnegan, 2004; Kubiczek and Mellen,
2004).
The first postmortem to determine the cause of a suspicious death took place
in Bologna in 1302. A local man called Azzolino collapsed and died suddenly
after a meal and his body very quickly became bloated whilst his skin turned
olive and then black. Azzolino had many enemies and his family believed that
he had been poisoned. A famous surgeon, Bartolomeo de Varignana, was called
upon to determine the cause and he was permitted to undertake an autopsy. He
concluded that Azzolino had died as a consequence of an accummulation of
blood in veins of the liver and that the death was therefore not suspicious.
Although this case set a precedent, there are relatively few records from the fol-
lowing centuries of autopsies being undertaken to determine the cause of death
in suspicious circumstances.
The first book on forensic medicine may have been that written by the Chinese
physician Hsu Chich-Ts’si in the sixth century AD but this has since been lost.
Subsequently, in 1247, the Chinese magistrate Sung Tz’u wrote a treatise enti-
tled ‘Xi Yuan Ji Lu’ that is usually translated as ‘The Washing Away of Wrongs’,
and this is generally accepted as being the first forensic textbook (Sung and
McKnight, 1981; Peng and Pounder, 1998). Sung Tz’u would also appear to be
the first person to apply an understanding of biology to a criminal investigation
as he relates how he identified the person guilty of a murder by observing the
swarms of flies attracted to the bloodstains on the man’s sickle. In Europe,
medical knowledge advanced slowly over the centuries and forensic medicine
really only started to be identified as a separate branch of medicine in the 1700s
(Chapenoire and Benezech, 2003). The French physician Francois-Emanuel
Foderé (1764–1835) produced a landmark three-volume publication in 1799
entitled Les lois éclairées par les sciences physiques: ou Traité de médecine-légale
et d’hygiène publique that is recognized as a major advancement in forensic
medicine. In 1802, the first chair in Forensic Medicine in the UK was estab-
lished at Edinburgh University and in 1821 John Gordon Smith wrote the first
book on forensic medicine in the English language entitled ‘The Principles of
Forensic Medicine’.
Animals and plants have always played a role in human affairs, quite liter-
ally in the case of pubic lice, and have been involved in legal wrangles ever since
the first courts were convened. Disputes over ownership, the destruction of crops
and the stealing or killing of domestic animals can be found in many of the ear-
liest records. For example, Hammurabi, who reigned over Babylonia during
1792–1750 BC, codified many laws relating to property and injury that subse-
quently became the basis of Mosaic Law. Amongst these laws it was stated that
anyone stealing an animal belonging to a freedman must pay back tenfold,
whilst if the animal belonged to the court or a god then he had to pay back
thirtyfold. In the absence of a money-based economy, the paying of animals and
plants as fines was commonplace whilst humans have always been sadistically
inventive in their use of animals as executioners to kill condemned prisoners.
The Romans threw Christians (and others) to the lions, whilst in the 1920s and
1930s prisoners in Siberian gulags were tied to posts and left to be exsan-
guinated by the hoards of mosquitoes (Applebaum, 2004). Animals have also
found themselves in the dock accused of various crimes. In the Middle Ages
there were several cases in which pigs, donkeys and other animals were exe-
cuted by the public hangman following their trial for murder or sodomy. The
judicial process was considered important and the animals were appointed a
lawyer to defend them and they were tried and punished like any human.
In 1576, the hangman brought shame on the German town of Schweinfurt by
publicly hanging a pig in the custody of the court before due process had taken
place. He never worked in the town again and his behaviour is said to have
given rise to the term ‘Schweinfurter Sauhenker’ (Schweinfurt sow hangman) to
describe a disreputable scoundrel (Evans, 1906). However, the phrase has now
fallen out of fashion. Today, it is the owner of a dangerous animal who is pros-
ecuted when it wounds or kills someone, although it may still find itself facing
the death penalty.
During the nineteenth century, a number of French workers made detailed
observations on the sequence of invertebrate colonization of human corpses in
cemeteries and attempts were made to use this knowledge to determine the time
since death in murder investigations (Benecke, 2001). Thereafter, invertebrates
were used to provide evidence in a sporadic number of murder investigations
but it was not until the 1980s that their potential was widely recognized. Part
of the reason for the slow development is the problem of carrying out research
that can be applied to real-case situations. The body of the traditional experi-
mental animal, the laboratory rat, bears so little resemblance to that of a human
being that it is difficult to draw meaningful comparisons from its decay and col-
onization by invertebrates. Pigs, and in particular foetal pigs, are therefore the
forensic scientists’ usual choice of corpse although America (where else?) has a
‘Body Farm’ in which dead humans can be observed decaying under a variety
of ‘real life (death?) situations’ (Bass and Jefferson, 2003). Leaving any animal
to decay inevitably results in a bad smell and attracts flies, so it requires access
to land far from human habitation. It also often requires the body to be pro-
tected from birds, dogs and rats that could drag it away. Consequently, it is dif-
ficult both to obtain meaningful replicates and to leave the bodies in a ‘normal’
environment. Even more importantly, these types of experiments conflict with
European Union Animal By Products Regulations that require the bodies of dead
farm and domestic animals to be disposed of appropriately to avoid the spread
of disease – and leaving a dead pig to moulder on the ground clearly contra-
venes these.
The use of animals other than insects in forensic investigations has proceeded
more slowly and that of plant-based evidence has been slower still. The first use
of pollen analysis in a criminal trial appears to have taken place in 1959
(Erdtman, 1969) and although not widely used in criminal trials since then its
potential is now being increasingly recognized (Coyle, 2004). By contrast, the
use of plants and other organisms in archaeological investigations has been
routine for many years.
The use of molecular biology in forensic science is now well established and
it is an accepted procedure for the identification of individuals. This is usually
on the basis of DNA recovered from blood and other body fluids or tissues such
as bone marrow, and Jobling and Gill (2004) provide a thorough review of
current procedures and how things may develop in the future. The use of molec-
ular biology for forensic examination of non-human DNA is less advanced,
although this situation will probably improve in the near future as DNA
databases become established. When this happens, forensic biology can be
expected to play an even larger part in legal proceedings, especially in relation
to the illegal trade in protected species, fraud (e.g. false insurance or subsidy
claims and mislabelling of food), rustling (horses and farm animals are fre-
quently the target of thieves) and cases of animal cruelty.
One of the major stumbling blocks to the use of biological evidence in English
trials is the nature of the legal system (Pamplin, 2004). In a criminal prosecu-
tion case, the court has to be sure ‘beyond all reasonable doubt’ before it can
return a guilty verdict. The court therefore requires a level of certainty that
science can rarely provide. Indeed, science is based upon hypotheses and a sci-
entific hypothesis is one that can be proved wrong – provided that one can find
the evidence. Organisms are acted upon by numerous internal and external
factors and therefore the evidence based upon them usually has to have quali-
fications attached to it. For example, suppose that the pollen profile found on
mud attached to the suspect’s shoes matched that found at the site of the crime:
this suggests a possible association but it would be impossible to state beyond
reasonable doubt that there are not other sites that might have similar profiles
– unlikely perhaps, but not beyond doubt. Lawyers are, quite correctly, experts
at exploiting the potential weaknesses of biological evidence because it is seldom
possible for one to state that there is no alternative explanation for the findings
or an event would never happen. Within civil courts, biological evidence has
greater potential because here the ‘burden of proof’ is based upon ‘the balance
of probabilities’.
This book is intended for undergraduates who may have a limited background
in biology and not for the practicing forensic scientist. I have therefore
attempted to keep the terminology simple whilst still explaining how an under-
standing of biological characteristics can be used to provide evidence. With such
a large subject base, it is impossible to cover all topics in depth and readers
wishing to identify a maggot or undertake polymerase chain reaction analysis
should consult one of the more advanced specialist texts in the appropriate area.
Similarly, those wishing more detailed coverage of individual cases would be
advised to consult the excellent books by Erzinclioglu (2000), Goff (2000),
Greenberg and Kunich (2002) and Smith (1986). Where information would not
otherwise be easily accessible to undergraduate students, I have made extensive
use of web-based material although the usual caveats apply to such sources.
At the start of each chapter, I have produced a series of ‘objectives’ to illus-
trate the material covered. They are written in the style of examination essay
questions, so that the reader might use them as part of a self-assessment revi-
sion exercise. Similarly, at the end of each chapter I have produced a number
of short-answer questions to test knowledge and recall of factual information.
Also at the end of each chapter, I have made some suggestions for undergrad-
uate projects. Because the usefulness of biological material as forensic evidence
depends on a thorough understanding of basic biological processes and the
factors that affect them, there is plenty of scope for simple projects based upon
identifying species composition or measuring growth rates. Obviously, for the
majority of student projects, cost, time and facilities will be serious constraints;
DNA analysis can be extremely expensive and requires specialist equipment.
Similarly, the opportunities to work with human tissues or suitably sized pigs
may not exist. However, worthwhile work can still be done using the bodies of
laboratory rats and mice or meat and bones bought from a butcher as substi-
tute corpses, with plants and invertebrates as sources of evidence.