Medical Detectives (44 page)

Authors: Robin Odell

BOOK: Medical Detectives

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CYANOSIS:
Condition in which the skin of the face and extremities of the body take on a bluish tinge due to interference with breathing, blockage of the airways and lack of oxygen entering the lungs. It is a feature of asphyxia.

DUM-DUM BULLETS:
Expanding bullets are intended to reduce penetration when they hit their target and massively increase wound damage. They are so named after the Dum-dum arsenal in India where they were first contrived by the British military. Soft-nosed bullets can be modified by cutting a cross-shape in the lead using a knife or saw. Such ammunition was first used at the Battle of Omdurman in 1898 by the British forces under the command of General Kitchener. The Hague Convention in 1899 prohibited the military use of dum-dum ammunition.

EXHUMATION:
Disinterring or exhuming a buried body is often a necessary procedure in the course of a murder enquiry. Disputed cause of death or questions about identity may also necessitate exhumation. For an exhumation request to be granted, authorisation is required from a coroner or the Home Office. The procedure may prove significant in cases of suspected poisoning where analysis of organs and tissue samples from the exhumed corpse reveal traces of poisonous substances.

FORENSIC BALLISTICS:
The possibility of relating bullets to the weapons that fired them was verified in 1889 by a French scientist, Alexandre Lacassagne. He successfully matched the rifling marks in a bullet taken from a victim’s body, with the rifling grooves in the barrel of the murder weapon. From these beginnings, forensic ballistics grew into an exact science, more descriptively known as firearms examination. The investigation of a crime scene shooting includes determining the respective positions of victim and shooter, examining the wounds inflicted and microscopic study of bullets, cartridge cases and propellants. Minute examination of crime weapons, their rifling pattern and other characteristics, adds further forensic detail to aid crime investigation.

FORENSIC MEDICINE:
The application of every aspect of medical knowledge to meet legal requirements is called forensic medicine or medical jurisprudence. Forensic comes from the Latin word,
forensis,
meaning ‘of the forum’ and referring to the principle of making public the cause of death when a person dies. Since its earliest days as a branch of medicine, the field has broadened to include many other scientific disciplines as well as psychiatry, dentistry and anthropology. The job of the forensic pathologist is to determine cause of death and define the supporting medical facts which may be required in the interpretation of evidence in court.

GRAIN:
Supposedly named after a grain of wheat and dating back four centuries, this is the smallest unit of mass in the English system. It was incorporated in the apothecaries’ weights used by pharmacists in the nineteenth century but is now obsolete, being superceded by the introduction of metric measurements in the 1960s. One grain is equivalent to 65 milligrams.

HISTOLOGY:
Microscopic study of the cellular structure of the tissues of the body. Thin sections of tissue are mounted on glass slides and stained with chemicals to highlight their detailed structure and any irregularities. Histological examination of tissue samples taken at post-mortem is a routine pathological procedure.

HYOID BONE:
A horseshoe-shaped bone located at the base of the tongue and above the thyroid cartilage in the larynx or voice box. It has four projections or horns, called the greater and lesser cornua. These may break in cases of strangulation when pressure is put on the larynx. A broken hyoid bone is a feature that forensic pathologists look for in cases of suspected strangulation.

HYOSCINE:
A vegetable alkaloid belonging to the
Solanaceae
family which includes henbane, belladonna and deadly nightshade. It has been used medicinally to treat anxiety, as its action is to depress the body’s central nervous system. Hyoscine is rapidly absorbed through the mucous membranes when a fatal dose causes respiratory failure and stops the heart. A fatal dose may be as low as 8 to 10 milligrams. It is sometimes called scopolamine and referred to as a ‘truth drug’.

LIVIDITY:
Also known as
Livor mortis
, hypostasis or, simply, as post-mortem staining. It is a process which begins immediately after death when the blood in the body sinks to the lowest point. When the heart stops pumping, blood coagulates in the veins and arteries giving rise to livid patches on the skin. Lividity occurs in the underlying parts of the body which are not in contact with a hard surface, typically the back of the neck, the thighs and small of the back. The internal organs are also affected, as gravity causes the blood to flow down to the lowest parts. The significance of lividity to the forensic examiner is that it helps to determine whether or not a body has been moved after death.

MARSH TEST:
In 1836, James Marsh, a scientist working at Woolwich Arsenal, developed a method for identifying arsenic. By converting traces of arsenic into arsine gas and directing it onto a polished surface, he produced a metallic deposit or mirror. The test, which is highly sensitive and capable of detecting very small traces of arsenic, represented a breakthrough in the investigation of cases where poisoning was suspected.

PETECHIAE:
Small haemorrhages, also called Tardieu spots, after the French doctor who first described them in 1870. The appearance of petechial haemorrhages in the skin of the face and on the heart and lungs is indicative of death by asphyxia. Severe compression of veins in the neck, or a struggle to breathe, causes the capillaries to burst and form these tiny, but distinctive, effusions of blood.

PHOSPHORUS POISONING:
An irritant poison in its yellow form traditionally used in the manufacture of matches and products to kill vermin. By contrast, red phosphorus is inert. Phosphorus poisoning creates symptoms similar to those of a bilious attack; burning sensation in the throat, vomiting and diarrhoea. A feature of such poisoning is the smell of garlic. This is evident in the breath of a person suffering poisonous effects and is also noticeable once the body cavity is opened for post-mortem examination. The pathological appearance of the internal organs may simulate natural disease. Petechiae are observed on the lungs and the liver is enlarged. A fatal does is around 2 grains.

POST-MORTEM:
The post-mortem examination, also known as an autopsy or necropsy, is an important procedure carried out by the forensic pathologist to determine cause of death. In 1861, Dr William Guy, Professor of Forensic Medicine at King’s College, London, noted what he called ‘The great rule to be observed in conducting post-mortems’. It was, ‘to examine every cavity and every important organ of the body … ’, to which he added, ‘even when the cause of death is obvious’. His point was that any omission could be exploited later in court to suggest that cause of death lay in some uninvestigated part of the body.

PRECIPITIN TEST:
In 1901, Dr Paul Uhlenhuth, a German scientist, developed the first test capable of distinguishing human from animal blood. By injecting protein from chicken eggs into rabbits, which responded by producing anti-bodies, he developed a serum whereby proteins in blood are precipitated and can be identified. A drop of anti-human serum is added to suspect blood which will precipitate if it is of human origin. His achievement represented a breakthrough in the scientific investigation of crime. The test is extremely sensitive and requires only a small sample of blood.

RIGOR MORTIS:
After death, the muscles of the body become rigid and fixed in a rigor, hence the term ‘stiff’ to describe a corpse. This is one of the classic signs of death which arises from coagulation of protein and shortening of the muscles. It is evident first in the eyelids and lower jaw and spreads progressively throughout the body. The process starts within five hours of death and is complete within twelve to eighteen hours. It then slowly disappears as chemical changes occur prompting the onset of decomposition. The state of rigor mortis as an indication of time of death is taken into consideration by the forensic examiner.

STATUS LYMPHATICUS:
The thymus gland, located in the upper part of the chest, is a ductless organ chiefly concerned with the body’s immune responses. It reaches its full size at the age of two years and then gradually shrinks. Enlargement of the thymus and associated lymph nodes can predispose a child to sudden, unexpected death. Overgrowth of the thymus may put pressure on related parts of the nervous system and blood supply. In association with other factors, such as shock, this condition may result in sudden death. Doctors disagree about the nature of status lymphaticus, but the generally accepted view is that it cannot by itself be a cause of death.

TIME OF DEATH (TOD):
This is one of the first questions confronting the forensic pathologist. While lividity and rigor mortis may be taken into account, the most reliable means of establishing TOD is to measure the rate of body cooling. Rectal temperature is measured at timed intervals, using a low-reading thermometer. A rule-of-thumb guide is that a body will lose 1.5 degrees F of heat every hour. The rate of cooling depends on many variable factors; whether the body is clothed, its physical condition (well-nourished or obese), the presence of disease, and environmental factors, such as indoors or out, and season of the year. The examiner plots a graph from timed temperature recordings to establish the rate of cooling and arrive at an estimated TOD.

VITAL REACTION:
The pathologist will seek to establish whether injuries on a body were inflicted before, or sustained after, death. When the body receives an injury, its natural defences respond by sending white blood cells (leucocytes) to the site to fight infection and repair damaged tissues. This is known as vital reaction. Microscopic examination of tissue samples taken from the injury site will help to determine whether the wound was caused ante-mortem or post-mortem. Where vital reaction is evident, the injury will have been caused during life.

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