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Azaria Chamberlain
Probably one of the most famous or infamous cases in which blood
stains played a key role was that of Azaria Chamberlain. The nature
of "blood" stains in the Chamberlain's car was one of the crucial
pieces of evidence initially used to convict then later clear the
Chamberlains of murder. Not unusually forensic science played the
role of both villain and hero in the hands of different
practitioners.
Petty theft
While the public, and often the police, see forensic science as
being the way to catch the criminal it is more than likely to prove
eliminate a suspect from an investigation and so show their
innocence.
A different sort of innocent victim was discovered in the English
Midlands, when a police officer reported the case of a young child
thought to have been attacked and raped in bed. Specimens were
rushed to the forensic laboratory - where a simple test startled the
serologists. The "bloodstains" were those of a piece of plum tart
the child had stolen from the kitchen. Her distress was due solely
to the fear of the police officer calling and discovering her petty
theft.
Changing Blood Groups
Bloodstains, types, and grades usually remain constant, but
sometimes they do not. One problem concerning antigens - substances
introduced into the blood to stimulate production of health
protecting antibodies, as in blood plasma - is that in recent years
scientists have realised that the red cells can actually acquire an
antigen of B type. This is caused by certain bacteria (proteus and
clostridium are examples) which produce substances similar to A, B,
and other blood group substances, and thus may result in false
grouping.
Leading in this research is the Department of Haematology and
Forensic Medicine of Britain's London Hospital Medical College, with
a team comprising GC Jenkins, J Brown, PJ Lincoln and BE Dodd. The
serologist Pierre Moureau who, in 1963 was called in to examine the
body of a child, which had been in water for sometime, inspired
them.
The police had reason to suspect the mother. But tests showed
that she had Group O blood, while Moureau's absorption-inhibition
tests at first showed the presence of A and B antigens in the dead
child. An O group mother, of course cannot have an AB group child.
Then Moureau repeated his tests. Gastric mucin autopsy (active
for Group A only) and cultures of blood showing bacteria and a B
activity led to the discovery that the B antigen had been acquired
…. In layman's terms, the blood group had changed after death.
In their research in the 1970s the London Hospital Medical
College team was later asked to solve a query about the dismembered
body of a woman found in the river Thames , London.
"The first part to be recovered." The team reported, "was the
thoracic region, and from this it was possible to obtain a limited
quantity of intact red cells, which were found to be Group O Rh
positive. From the pelvis, which remained in the water for a longer
period, no red cells were recovered, but muscle tissue gave
reactions of Group B. The blood groups, therefore, did not support
the conclusion that the previously discovered thorax and the (later
found) pelvis were from one and the same individual.
"However, the shape of the cut surfaces proved beyond a shadow of
doubt that the two parts belonged to each other, and this raised the
suspicion that the B reaction might be of bacteriological origin.
Further work confirmed this.."
Some common terms used in serology.
- agglutinogen - A substance that stimulates the formation of
specific antibodies, which causes clumping of cells that contain the
antigen or particles coated with the antigen.
- antibody - A protein that is produced in response to an antigen.
It is able to combine with and neutralize the antigen by causing it to
clot and precipitate out.
- antigen - A substance, usually a protein that stimulates the body
to produce antibodies against it.
- plasma - The fluid portion of the blood in which the particulate
components are suspended.
- platelets - A particle found in the bloodstream that binds to
fibrinogen at the site of a wound to begin the blood clotting process.
Platelets are formed in bone marrow, where they arise from cells
called megakaryocytes.
- red blood cells - Cell specialised for transport, having
a concentration of haemoglobin in the cytoplasm (and little
else).
- serology - A term which describes laboratory tests which employ a
specific antigen and serum antibody reactions. A science dealing with
serums and especially their reactions and properties.
- serum - The liquid portion of blood left over after all of the
cells have been removed.
- white blood cells - Cells which circulate in the blood and
lymphatic system and rest in the lymph glands and spleen. They are
part of the immune system responsible for both directly and
indirectly attacking foreign invaders of the body.
More Information
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