Blood spatter Essay
Blood spatter is a common form of physical evidence at a death scene, and is often of major relevance. It is not a field in which all forensic pathologists feel confident, as in some jurisdictions it is regarded as totally within the domain of the forensic scientist and in others, the crime scene investigator. It should be reasonably regarded as a shared topic, one understood by all players, as each expert has an individual slant on the subject, and can thus provide separate insights.
It is important to avoid evidence clashes. Examination and documentation of blood spatter, including what, where and how much, allows interpretation of the type and form of bleeding, and may provide a reconstruction of the incident and some surrounding circumstances. The form of report produced tends to vary with different departments, but usually is incorporated into the general scene report. Blood loss itself is due to breaches of blood vessels, and this may be due to natural disease processes or trauma.
Typical examples of natural disease-causing problems at crime scenes include bleeding from a varicose skin ulcer, which is at ankle or shin level, and bleeding from lung cancer, which produces coughed-up blood. Both of these may be associated with widespread blood deposition. Commonly, these kinds of cases are associated with some degree of cleaning up or self-help, of a type consistent with a solitary life style. The type of loss is dependent on the kind of blood vessels involved. Veins return blood to the heart, operate at low pressure and flow is at a constant rate.
A breach causes an ooze or pour of blood. On the other hand, arteries operate at high pressure and have a pulsatile flow. This produces a very variable flow rate, and a breach causes a spray or spurt of blood. The normal blood pressure peak and trough is 120/80mmHg at rest, but can be as high as 180-200mmHg with strenuous activity or stress, excluding any disease process. Obviously, this level may be expected in violent deaths. As veins and arteries commonly run parallel to each other, both types of vessels may be damaged at once.
The size of vessel is also important, as small vessels will produce little blood, whereas the major vessels can bleed catastrophically. An arbitrary level of 200ml has been defined as the cut-off between a small and a large volume. The pathologist can rarely estimate the volume directly at the scene with any great degree of accuracy. The estimate may have to be done indirectly by crime scene examiners, such as by weighing areas of soaked carpet, and comparing this with dry areas. Classifications of Blood Stains:
The appearance and the size of the blood patterns depend on the force by which they were created. When a sort of an object comes into direct contact with the blood, the force by which that object makes contact moves the blood and enhances its velocity. In some fashion the blood must react to this force transfer. Velocity is calculated in meters per second. There can be an evidence of three forms of blood spatter at a crime scene, high, medium or low blood spatter or a mix combination of these.
The predictable process of categorizing blood stains was based on the connection between the speed of the force pressuring the blood drop or source that administer the individuality and dimension and distance of the resulting bloodstains. The three essential grouping of stain groups which were used based on the idea that the dimension of the blood stain being inversely comparative to the power useful to the still blood. Low Velocity Blood Spatter LVBS (Low Velocity Blood Spatters) are stains of blood which are created when the cause of blood is subjected to energy with the speed of up to 5 ft/sec.
Major stains calculate normally 4mm in distance or superior. Medium Velocity Blood Spatter MVIS (Medium Velocity Blood Spatter) are stains of blood which are formed when the cause of blood is subjected to a might with a speed in between the range of 6 to 25 ft/sec. The distances of the consequential stains are in the mass range of 1 to 3 mm, even though larger and smaller bloodstains may be there. Stains in this group are normally connected with beatings and stabbings. High Velocity Blood Spatter HVBS (High Velocity Blood Spatter) are stains of blood formed when the cause of blood is subjected to a power with a speed of more than 100ft/sec.
The width of the spatter is mainly less than 1mm, although larger and smaller bloodstains are frequently experiential within the outline. Bloodstains in this group are usually related with gun shots and explosions. Other device that formed bloodstains within the mass range of the usual high and medium velocities such as expiratory blood and satellite spatter bloodstains were not valued to the level that misunderstanding might and do occur. Most of the bloodstains forecasters have selected to stop this conservative terms and categorization for a more holistic advancement to bloodstain categorization.
The subject that formed the rethinking of the conservative categorization of high-medium-low velocity was the diameter of sizes of stain among the high and medium velocity group and the understanding that devices other than stabbings, gunshots and beatings often formed stains with the dimension ranges within these groups. The pattern and bloodstains are confidential based on their substantial features of distribution, location, size, concentration and shape into inactive stains, splash stains or distorted stains.
These are more confidential relation to method that may create stains with that uniqueness with mention to relevant scene, medicinal and case related history and facts of the proof. The forecaster than may be able to set up the exact method by which the outline was formed. More Analysis on the three classifications An abrasion or superficial laceration involves large numbers of very small to small vessels. This produces diffuse velocity from the whole area, and neither a pour nor a spray of blood would be expected. Incision of a superficial artery, such as in the wrist, involves larger vessels, with a small area of origin.
This produces mainly a low velocity of blood due to pumping or spurting. A stab of a deep artery, as in the thigh, may mean involvement of a larger deep vessel. Here the presence of overlying tissues will interfere with the production of a spray, and the blood exits as a rapid pour, usually without spurting. However, there is usually still a clearly pulsatile element. But again this would be said as a low velocity blood spatter. The size of blood spots relates to the impulse of dispersal. Low velocity blood spatter such as venous bleeding, will produce large blood spots.
A medium velocity blood spatter, such as produced by the use of a blunt instrument, will produce finer spots. High velocity blood spatter, as in gunshot injuries for example, will produce a fine spray. This can also be used in interpretation, as in the case of a crewman missing after an on-board explosion. There were several areas of very fine blood spray near the relevant hatch cover, and also on a broken ship’s railing. This clearly indicated that the deceased had been hit by the swinging hatch cover, and had broken the railing by force of his impact with it, during the course of being thrown overboard.
Some knowledge of the injury pattern will produce the best results in interpretation. For example a slash of the neck might be expected to produce arterial spurts from large superficial vessels. A stab of chest could produce a medium flow, but if the stab is small or angulated, producing a degree of sealing, there may be little external bleeding. For example, multiple heart and aortic stabs with a skewer have been seen to produce only occasional external drops of blood. A stab of the lung may have the combination of direct bleeding from the stab and the expiration of blood mixed with air.
Projected bleeding can also occur from mouth and nose following a gunshot wound of the head. During the bleeding process, the blood may be around the injury itself, and be capable of making contact impressions, or may have been projected away from the injury, and no longer be on the body at all. This blood may be around the body, and situated on bedding, furnishings, walls or carpet. The type of patterning will provide the pathologist with insights of where and how the deceased had moved. The blood may be on objects at the scene such as a weapon or a vehicle.
The position, patterning and extent may indicate which part of the object caused the injury, and in turn, this may indicate the position of the deceased at the time of sustaining this injury. There may be minimal blood present at the scene, or what appears to be an inadequate amount, in view of the injuries. This may indicate that this is a secondary scene, and that the primary scene must be searched for elsewhere. Produce a fine spatter of blood at low level, with the last drops producing the greatest effect.
This may outline the feet on the floor, and will also be present on the inner borders of the feet and the tops of the feet. The blood on the feet may subsequently be transferred elsewhere. The target surface is of major importance, and the effect is far less on a carpet than it would be on tiles, due to the reduced pool effect. Another significant aspect relates to blood which has been deposited from an injury onto a weapon, and is then cast off by the centrifugal force of swinging the weapon again. This may leave blood trails on ceilings or on high walls. There are various forms through which people can be killed.
Listed are the few and the classification of which Velocity Blood stain it belongs to: Shootings (Medium and mostly high level Blood Spatter Velocity) Apart from the normal documentation of the scene, it is necessary to consider a number of specific matters. The pathologist must determine if the victim has moved during the course of the shooting, or has shown signs of activity afterwards. This can be done by noting the position of the body, the accessibility of the entry sites in the current body position, the presence of bullets or markings near the exit sites, and blood or tissue spatter patterns.
There is usually little back spatter, but there may be considerable forward spatter, especially with more powerful weapons. It is worth bearing in mind that there may also be significant spatter extending from gas splits in the skin, and this could be at right angles to the main bullet track. Knife (Medium Velocity Blood Spatter) As mentioned above, the possibility of movement has to be considered. The volume of blood coming from an injury will depend on factors such as its type, situation and coverings, but if these are held in mind, then useful information can be gathered in order to reconstruct the incident.
A knife or other sharp weapon is unlikely to cause damage to the scene, except in the most violent incidents, but it may be wiped or cleaned on the victim’s clothing or on furnishings, leaving a bloody outline. Axe (Mostly Medium Blood Spatter and at time High velocity) Because of the type of injury produced, these scenes tend to be very bloody. As there is a tendency to inflict multiple blows, there may also be evidence of the way in which these injuries were inflicted, as left by the spatter patterns. These patterns will frequently include cast-off spatter, as well as medium impulse spatter.
There may even be loose fragments of soft tissue, bone or teeth. There maybe damage to the scene, particularly near to the body, due to missed hits. Fists and feet (Low velocity Blood Spatter) Assaults by kicking or stamping maybe associated with considerable contamination of the crime scene. This maybe in the form of a low-level blood spatter which may be evident up to a meter or so above ground level. Evidence of the type and position of an earlier phase of the assault is to be looked for, and blood pools that are separate from the final position of the body indicate periods of immobility.
The ground surface has to be considered from the point of view of its being the possible anvil opposite some of the injuries, and thus help to interpret the assault. Footprint patterns may help to provide information as to whether bare or shod feet were used. Explosion (High Velocity Blood Spatter) Explosion scenes may extend from those where only a gram or two of explosive material is involved, to those involving tonnes of material. The pathologist’s approach will vary accordingly.
Where a small quantity of material is involved, the pathologist should attempt to assess if there was any movement of the body from its original site to the point at which it is found. Blood and tissue spatter is most valuable here. The crime scene findings must be correlated with the burns and particulate damage later identified at the autopsy. The presence and role of any primary or secondary projectiles must be assessed. The author was involved in the investigation of an explosion on board a ship, where a crewman caused an explosion that blew him overboard.
The body was not recovered, but damage to a hatch cover and the ships rail, both with deposition of high-impulse blood spatter and small tissue fragments indicated the extreme nature of the trauma that must have been sustained. Fragmentary body remains may be all that is recovered following a large explosion. As these may be covered with cement dust or other building materials, recognition of these remains at the scene may prove to be difficult, but this task is usually easier for a pathologist than other investigators. Work Cited Page • Book Title: The Practice of Crime Scene Investigation.
Contributors: John Horswell – author. Publisher: CRC Press. Place of Publication: Boca Raton, FL. Publication Year: 2004. • Catten Ely (2000) Blood Spatter, What is it? From Suite 101. Retrieved on October 23, 2007, from http://www. suite101. com/article. cfm/crime_stories/34498 • Louis L Akin (2005) Blood spatter interpretation at crime and accident scenes: a basic approach. (Focus on Forensics): An article from: The FBI Law Enforcement Bulletin. Publication: The FBI Law Enforcement Bulletin (Magazine/Journal) • Book Title Introduction to forensic science & criminalistics (2007) Publishers McGraw-Hill • James, Stuart H.
(2005) Principles of bloodstain analysis; theory and practice. Publisher CRC Press • Blood Spatter (2006) Department of Forensic Medicine, University of Dundee. Retrieved on October 23, 2007 from http://www. dundee. ac. uk/forensicmedicine/notes/Bloodspatter. htm • Base Pair (2004), Blood Spatter Pattern Analysis. Retrieved on October 23, 2007, from http://www. tx. ncsu. edu/Science_Olympiad/Coaches_workshop/2007%20Presentations/Blood%20Spatter%20Analysis. doc • Blood and Stain Analysis. Retrieved on October 23, 2007, from http://home. iprimus. com. au/ararapaj/craigslea_testbed/Forensic%20Web%20Test%20Site/blood_analysis. htm