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.
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 â€¦. 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.