THE ATTIC : Bloodstains Date Added AUG 2002 At the scene of most violent homicides there is an overwhelming presence of blood - not only on the body of the victim and any murder weapon that may have been left, but if the crime was committed in a building, on walls, floor, furnishings and furniture surfaces, even the ceiling. In such cases it is important that a forensic scientist experienced in interpreting bloodstains is summoned to the scene as a great deal can be deduced from the quantity, distribution and shape of the stains. Drops Found on horizontal surfaces, caused by blood dripping from directly above. The shape of the drop will change according to the height from which it has fallen, the crenellations or 'staring' being more pronounced the greater the fall. Splashes Most commonly occurring where droplets of blood have travelled through the air - perhaps as a bludgeoning instrument is swung - and hit the surface such as a wall at an angle. This tends to leave a stain shaped like an elongated exclamation mark, the 'blob' indicating the direction of travel. These stains may provide useful information as to the scenes of assault where a victim has been struck in more than one location, and the actual location of the assault when a body has been moved after death. Spurts Because blood is pumped by the heart around the body under great pressure it is obvious that if a major vein or artery is severed there will be a forceful outflow of blood which,  in addition to staining the attacker, will also travel some distance around the victim - up walls, sometimes even to the ceiling. It follows that if the victim is already dead (that is to say the heart has stopped pumping,) then injuries inflicted will not result in such widespread 'spurting'. This fact could be an important indicator in distinguishing the scene of a killing from that of a subsequent dismemberment. Pools A pool of blood marks the spot where a heavily bleeding victim will have lain dead or, if more than one pool is apparent with a single victim, where the victim has dragged themselves or someone has dragged them from one place to another, remaining sufficiently long enough in each location to form a pool. The route between pools will be indicated by blood smears or drops. Smears Smears can be left either by the wounded victim or their assailant stained with fresh blood, gripping or brushing against the sides of furniture, doors, walls, etc., depositing blood. It could also be caused by the smearing of existing fresh stains. Trails If a bloody corpse is moved from the scene of the killing to another location by dragging it will leave a smeared trail along the route; a body carried from one place to another may leave a trail of 'drops', as would an injured person moving from one place to another. Old Bloodstains In the majority of homicide cases no attempt has been made to dispose of the victim's remains permanently or to clean the scene of the crime. Bodies are for the most part left where they fall, surrounded by the mess and disorder created by their untimely death. In those cases where a killer, anxious to 'get away with murder', takes the trouble to try to thwart justice by covering their tracks, they are confronted by the bewildering problems of the bloody corpse. Apart from the psychological problem created by a profusely bleeding body, murder victims present their killers with appalling logistical difficulties. Blood accounts for around nine percent of the human bodyweight - in effect about ten pints. When spilt it is, with modern detection techniques, impossible to eradicate. Bleach, that old kitchen standby so beloved of fictional killers, simply stains the blood a pale greeny-brown. In fact, cold water is by far the best solvent for stubborn bloodstains - hot water having the opposite effect of fixing the stain. Even in cases where all trace has apparently been removed - say on ceramic or plastic - there are chemicals which, if sprayed as a mist on the surface, will reveal the former presence of blood. The reagent leuco-malachite green will indicate traces of diluted blood so as to be invisible to the eye, and sprays of orthotolidine and phenolphthalein produce the same result - the former revealing 'invisible' stains as bright green, the latter pink. More frequently the suspicions of the scenes of crime experts are aroused by those minute tell tale dark spots which have escaped the murderers attention. However, because blood itself undergoes colour changes in certain circumstance, and many other substances can look like blood, there is the need for a simple, rapid, on the spot test to ensure that only blood stains are marked for later examination. The most common is the so called Kastle-Meyer test where a piece of filter paper is rubbed on the stain so that some of the substance transfers to the paper; this is then treated with a drop in turn of the reagents alcohol, phenolphthalein and hydrogen peroxide. If the paper shows pink, blood is present, and the test is sensitive enough to give positive results even minute samples. BACK TO TOP

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