Bloodstain Pattern Analysis
A nice young female is quietly walking back to her apartment late in the night, when she feels someone watching her. She quickly whips around to find that she is staring in the pure darkness. Nothing is there, she thinks to herself, but she can still feel the pure eeriness of someone watching her. She quickens her pace to make it to her apartment safely, but when she is about to be safely behind a locked door, something comes crashing down on her head. Blood goes splattering everywhere. The criminal investigators come in the next morning to investigate what happened to this innocent lady. They put all their knowledge together and decide to try to solve this case by using what? Bloodstain Pattern Analysis! Blood, the red liquid that
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is pumped through the arteries and is made up of many different cells, is forced out of the body in accidents and crimes. Each specie has different consistency of blood. Scientist's results are based on Homo sapiens blood. If they were to use animal blood the results would never come to be the same. When thinking of bloodstain pattern analysis, one probably thinks, "Hmmm must be some complicated forensic science technology!" Actually, it is not; forensic scientists have used it since the 1890's.
Bloodstain pattern analysis has been around for as long as fingerprinting has been used as a means to identify criminals. Hans Gross, in his 1892 papers, "Criminal Investigations," described bloodstains found at crime scenes and that the direction of the bloodstains could be determined by the shape of the bloodstain. Balthazard, a French criminal analyst, found that the angle a bloodstain stuck the surface could be determined by dividing the width of a bloodstain by the length. This helped in determining the location from which the bloodstain came from. Eventually, they put this worked under the category of forensic science. In defining bloodstain pattern analysis, some might say, "Show what happened at the crime scene through bloodstains, and there it is bloodstain pattern analysis." Technically that is incorrect, but basically that is what it is. According to the book Blood Stain Analysis by Terry L. Laber and Barton P. Epstein, it is the reconstructing of events causing the bloodstain patterns to be …show more content…
found. In a crime involving bloodshed, a multitude of information can be gathered from using bloodstain pattern analysis. All of the following things can be learned using this forensic science: the location and orientation of the people and objects at the time the incident occurred, the movements of the person or object during the bloodshed, the place where the blood originated, the number of impacts and the event in which it took place, whether or not the suspect was bleeding, the position of the victim, and if a struggle took place in the event. When crimes happen with no witnesses, the forensic evidence at the scene becomes the most important to true witness of all. Forensics scientists use this technology to prove what happened at the scene. An important rule is the smaller the droplets of blood, the greater the force that made it. Also, air resistance affects smaller droplets of blood According to scientists, there are five main bloodstain patterns to look for
The impact pattern is the result of blood from a blow and hard impact.
Then there is a cast off pattern, which is a result of blood being flung from an object in motion
The gunshot pattern is a result from a gunshot
There is the projected patter, which is a result from loss of large amounts of blood, such as bleeding from a main artery
And last of all, the transfer patter, which is a pattern, which is a pattern when a non-bloody object comes in contact with a bloody object.
Blood is a very uniform material from the aerodynamic standpoint. Blood's ability to reproduce specific patterns is not affected significantly by sex, age, or diseases that the person bleeding might have. Since blood is shed from a body at constant temperature and is exposed to an external environment for such a short time, atmospheric temperature, pressure and humidity usually have no measurable effect on blood's behavior. Alcohol and drug used will also not affect bloodstains. During the search for stains, in some cases investigators find it extremely difficult to find blood. When they are trained, they are given pointers on how to find them. A dried, but somewhat fresh bloodstain generally has a reddish-brown color and is glossy in contrast to, for example, it looks like a rust stain. In a very thin layer, the color might happen to be grayish-green. The gloss disappears slowly under the conditions of heat, exhaust, sunlight, wind, and weather, or as the result of trying to wash it away, the color then finally becomes gray. Bloodstains can, however, be other colors from red to brown to black, or they may appear green, blue, or grayish-white. The color and also the time taken preserve the pattern depend upon the surface it is on; the change is quicker on metal surfaces and slower on textiles. With some types of cloth, the blood soaks into the threads. Surface gloss is often less marked on the fabric. Bloodstains on wallpaper may show surprising colors because the blood is taking up color from the paper, or soaking in its print. Certain other stains made up of pigments, rust, tobacco, snuff, urine, feces, and other materials can be easily confused with bloodstains. In searching for bloodstains, marks should not be classified according to color and character since a stain that appears to stray from the normal character of a bloodstain may be composed of blood; instead one that resembles blood may be composed of some other substance. Since blood evidence at a crime scene can provide clues that might solve the case, it is important to document, collect, and preserve this type of evidence. Surgical gloves, ventilation masks, body suit, and according to the situation, precaution goggles, should all be worn when working with blood evidence. Smoking, eating, or drinking these areas should not be permitted. When documenting bloodstains, a description should be made of their form, color, position, and direction of splash and the estimated height of the fall. If the collection of evidence is done correctly, the evidence can be presented years later from the time of the crime. When collecting the evidence, little disturbance should be used. Bloodstains should be allowed to dry as much as possible before being moved or packaged. If not handled correctly, evidence containing bloodstains might crack or flake off. Of all the common types of evidence found at crimes scenes, blood is perhaps the most fragile. Bloodstains should be measured with a metric ruler, and depending on the size of the stain and magnifying glass should be used. The best way to preserve the appearance of bloodstains is through photography. Photographs showing overall, medium range and close-up views should be made. A scale should be included for the close-up photographs. Besides photography, a rough sketch is useful to show the general appearance of the stains as well as the relative position to other areas of the crime scene. The sketch should contain the location and direction of the stain. Theory behind bloodstain splatter analysis is simple: blood is a fluid and will respond to the laws of physics.
Even though rarely being the master key to the lock, bloodstain splatter analysis can be important in the complicated and mind boggling process of reconstructing a violent crime. Even though bloodstain splatter analysis isn't pinpoint accurate, experts still provide criminal analysts with good approximations of the position of both the victim and suspect. Now when talking about pinpoint accuracy, scientist are looking for an area the size of a volleyball or a head, even though with the technology and equipment they have today they could track it down to the size of a fist. This can be a crucial investment in deciding how to proceed with a
search. The fate of the impact angle of a bloodstain is one of the most important and vital tools in the interpretation and crime scene reconstruction. By telling the impact angles of a number bloodstains and sending them back to the same direction they came from, it is often possible to locate the source of the bloodstains with precision accuracy. Knowing the location of the source of the stains and the results of blood grouping tests will allow reconstruction of the sequence of events that produced the bloodstain patterns observed at the scene. When a drop of blood strikes a surface perpendicular to its line of flight, a circular stain results. When a blood drops strikes a surface, which is at an angle to it line of flight an elongated stain will result. The degree of elongation (length-to-width or width- to-length ration) is proportional to the angle of impact of the drop producing the stain. The length-to-width and width-to-length ratios of a bloodstain are independent of the dropping height and volume of the drop used. When blood receives a blow it will be broken into small drops and dispersed in many directions. The number, size and shape of the resulting bloodstains will depend largely upon the amount of blood available for spatter, the force of the impact and the shape and nature of the object striking the impact site. It takes two times for a bloodstain to occur. The first time there is a blow to the body it causes the blood to flow and the second time is when it happens. If there are numerous hits then there will be more extensive amounts of blood splattered. Because the impact spatter is influenced by several different factors, the impact stain patterns produced will vary from a few spatters to many spatters, from large stains to barely visible stains, and from round stains to very elongated stains. Increasing the force of impact increases the quantity of small diameter spatters. Attempting to relate the size of the stain to the amount of force can be difficult because several other factors dramatically affect the stain size. In conclusion, bloodstain pattern analysis is used in more cases than one would think. It is an extremely efficient tool to use in any case that involves bloodshed. As mentioned previously, this analysis is one of the easiest to use according to forensic scientists.
is pumped through the arteries and is made up of many different cells, is forced out of the body in accidents and crimes. Each specie has different consistency of blood. Scientist's results are based on Homo sapiens blood. If they were to use animal blood the results would never come to be the same. When thinking of bloodstain pattern analysis, one probably thinks, "Hmmm must be some complicated forensic science technology!" Actually, it is not; forensic scientists have used it since the 1890's.
Bloodstain pattern analysis has been around for as long as fingerprinting has been used as a means to identify criminals. Hans Gross, in his 1892 papers, "Criminal Investigations," described bloodstains found at crime scenes and that the direction of the bloodstains could be determined by the shape of the bloodstain. Balthazard, a French criminal analyst, found that the angle a bloodstain stuck the surface could be determined by dividing the width of a bloodstain by the length. This helped in determining the location from which the bloodstain came from. Eventually, they put this worked under the category of forensic science. In defining bloodstain pattern analysis, some might say, "Show what happened at the crime scene through bloodstains, and there it is bloodstain pattern analysis." Technically that is incorrect, but basically that is what it is. According to the book Blood Stain Analysis by Terry L. Laber and Barton P. Epstein, it is the reconstructing of events causing the bloodstain patterns to be …show more content…
found. In a crime involving bloodshed, a multitude of information can be gathered from using bloodstain pattern analysis. All of the following things can be learned using this forensic science: the location and orientation of the people and objects at the time the incident occurred, the movements of the person or object during the bloodshed, the place where the blood originated, the number of impacts and the event in which it took place, whether or not the suspect was bleeding, the position of the victim, and if a struggle took place in the event. When crimes happen with no witnesses, the forensic evidence at the scene becomes the most important to true witness of all. Forensics scientists use this technology to prove what happened at the scene. An important rule is the smaller the droplets of blood, the greater the force that made it. Also, air resistance affects smaller droplets of blood According to scientists, there are five main bloodstain patterns to look for
The impact pattern is the result of blood from a blow and hard impact.
Then there is a cast off pattern, which is a result of blood being flung from an object in motion
The gunshot pattern is a result from a gunshot
There is the projected patter, which is a result from loss of large amounts of blood, such as bleeding from a main artery
And last of all, the transfer patter, which is a pattern, which is a pattern when a non-bloody object comes in contact with a bloody object.
Blood is a very uniform material from the aerodynamic standpoint. Blood's ability to reproduce specific patterns is not affected significantly by sex, age, or diseases that the person bleeding might have. Since blood is shed from a body at constant temperature and is exposed to an external environment for such a short time, atmospheric temperature, pressure and humidity usually have no measurable effect on blood's behavior. Alcohol and drug used will also not affect bloodstains. During the search for stains, in some cases investigators find it extremely difficult to find blood. When they are trained, they are given pointers on how to find them. A dried, but somewhat fresh bloodstain generally has a reddish-brown color and is glossy in contrast to, for example, it looks like a rust stain. In a very thin layer, the color might happen to be grayish-green. The gloss disappears slowly under the conditions of heat, exhaust, sunlight, wind, and weather, or as the result of trying to wash it away, the color then finally becomes gray. Bloodstains can, however, be other colors from red to brown to black, or they may appear green, blue, or grayish-white. The color and also the time taken preserve the pattern depend upon the surface it is on; the change is quicker on metal surfaces and slower on textiles. With some types of cloth, the blood soaks into the threads. Surface gloss is often less marked on the fabric. Bloodstains on wallpaper may show surprising colors because the blood is taking up color from the paper, or soaking in its print. Certain other stains made up of pigments, rust, tobacco, snuff, urine, feces, and other materials can be easily confused with bloodstains. In searching for bloodstains, marks should not be classified according to color and character since a stain that appears to stray from the normal character of a bloodstain may be composed of blood; instead one that resembles blood may be composed of some other substance. Since blood evidence at a crime scene can provide clues that might solve the case, it is important to document, collect, and preserve this type of evidence. Surgical gloves, ventilation masks, body suit, and according to the situation, precaution goggles, should all be worn when working with blood evidence. Smoking, eating, or drinking these areas should not be permitted. When documenting bloodstains, a description should be made of their form, color, position, and direction of splash and the estimated height of the fall. If the collection of evidence is done correctly, the evidence can be presented years later from the time of the crime. When collecting the evidence, little disturbance should be used. Bloodstains should be allowed to dry as much as possible before being moved or packaged. If not handled correctly, evidence containing bloodstains might crack or flake off. Of all the common types of evidence found at crimes scenes, blood is perhaps the most fragile. Bloodstains should be measured with a metric ruler, and depending on the size of the stain and magnifying glass should be used. The best way to preserve the appearance of bloodstains is through photography. Photographs showing overall, medium range and close-up views should be made. A scale should be included for the close-up photographs. Besides photography, a rough sketch is useful to show the general appearance of the stains as well as the relative position to other areas of the crime scene. The sketch should contain the location and direction of the stain. Theory behind bloodstain splatter analysis is simple: blood is a fluid and will respond to the laws of physics.
Even though rarely being the master key to the lock, bloodstain splatter analysis can be important in the complicated and mind boggling process of reconstructing a violent crime. Even though bloodstain splatter analysis isn't pinpoint accurate, experts still provide criminal analysts with good approximations of the position of both the victim and suspect. Now when talking about pinpoint accuracy, scientist are looking for an area the size of a volleyball or a head, even though with the technology and equipment they have today they could track it down to the size of a fist. This can be a crucial investment in deciding how to proceed with a
search. The fate of the impact angle of a bloodstain is one of the most important and vital tools in the interpretation and crime scene reconstruction. By telling the impact angles of a number bloodstains and sending them back to the same direction they came from, it is often possible to locate the source of the bloodstains with precision accuracy. Knowing the location of the source of the stains and the results of blood grouping tests will allow reconstruction of the sequence of events that produced the bloodstain patterns observed at the scene. When a drop of blood strikes a surface perpendicular to its line of flight, a circular stain results. When a blood drops strikes a surface, which is at an angle to it line of flight an elongated stain will result. The degree of elongation (length-to-width or width- to-length ration) is proportional to the angle of impact of the drop producing the stain. The length-to-width and width-to-length ratios of a bloodstain are independent of the dropping height and volume of the drop used. When blood receives a blow it will be broken into small drops and dispersed in many directions. The number, size and shape of the resulting bloodstains will depend largely upon the amount of blood available for spatter, the force of the impact and the shape and nature of the object striking the impact site. It takes two times for a bloodstain to occur. The first time there is a blow to the body it causes the blood to flow and the second time is when it happens. If there are numerous hits then there will be more extensive amounts of blood splattered. Because the impact spatter is influenced by several different factors, the impact stain patterns produced will vary from a few spatters to many spatters, from large stains to barely visible stains, and from round stains to very elongated stains. Increasing the force of impact increases the quantity of small diameter spatters. Attempting to relate the size of the stain to the amount of force can be difficult because several other factors dramatically affect the stain size. In conclusion, bloodstain pattern analysis is used in more cases than one would think. It is an extremely efficient tool to use in any case that involves bloodshed. As mentioned previously, this analysis is one of the easiest to use according to forensic scientists.