Heinous crimes occur everyday. These have controversially stirred up the public’s interest in forensic science techniques. People are aware of the importance of evidence and how these can substantially affect the investigation process. Forensic science, throughout the years, has been a key component in resolving crimes. Forensic scientists, crime investigators, and police partake in the various duties and responsibilities in crime investigation. There are several departments in a crime laboratory having specialists who take charge of the evidence collected at the crime scene.
Through comprehensive analyses of DNA, blood, firearms, drugs, alcohol, and other tools which are done in full crime laboratories, strong evidence for the crime are established empirically. Specific techniques performed by crime investigators and forensic scientists are done with these tools (Bevel & Gardner, 1997). Benecke & Barksdale (2003) argue that forensic science claimed popularity worldwide due to advanced methods employed in criminal cases. These have helped determine the guilt or innocence of the defendant.
Investigation procedures have been trouble-free for police due to the advances in DNA sampling and testing, posing major importance in crime investigation. Blood typing and testing are the main job functions of a forensic serologist, who also analyzes other important body liquids such as semen, saliva, other body fluids and may or may not be involved with DNA typing. At present, blood seems to be the most important component both for medical or forensic purposes. At crime scenes, victims and suspects are easily associated through obtained blood samples and stains.
Bloodstain patterns are not only used to show the association of the victim and the assassin; position and movement during the crime can also be illustrated, who struck whom first, in what manner, upon establishment of the necessary information needed to reconstruct the crime scene. Such evidence prove the lack of veracity in defendants’ claims, which are eventually found to be mere alibis or self-proclaimed arguments. Indeed, this is a very effectual and reliable technology in crime investigation (Fisher, 2003).
The science of bloodstain pattern analysis applies scientific knowledge from other fields to solve practical problems. Bloodstain pattern analysis draws on biology, chemistry, math, and physics, as scientific disciplines. As long as an analyst follows a scientific process, this applied science can produce strong, solid evidence, making it an effective tool for investigators (Fisher, 2003). Blood is partly alkaline liquid, made up of water, cells, enzymes, proteins, and inorganic substances. It flows throughout the vascular system, transporting nourishment, oxygen, and waste.
Plasma is the fluid portion of the blood containing water and serum (which is yellowish and contains white cells and platelets). Red cells are the non-fluid portion of the blood, outnumbering the white cells (Stuart, 2005). Red cells and serum are very crucial elements for the carrying out the work of the forensic scientist. The freshness of the obtained blood sample can be assessed through serum; moreover, antibodies are also carried in it and such are also important in forensic analysis. More tests may be done with wet blood than dried blood; hence, wet blood has more value than a dried sample.
Traces of alcohol and drug content can only be tested from a wet blood sample. Within 3-5 minutes of exposure to air, blood starts drying up, changing its color. There are different blood forms, including pools, drops, smears or crust. The height and angle at which the blood sample fell off can be identified by its drop and form. The distances at which the blood fell can be reported through the forensic science of blood spatter analysis. If blood fell from a higher distance, it has more pronounced tendrils fraying off the edges, while a blood smear on the floor indicates the direction of the force of the blow.
Splatter tells the direction of the force, as it always moves toward the tail (Geberth, 1996). In 1875, different blood types had been discovered, but it was not until 1901 when Karl Landsteined formalized blood groupings, labeling them as type A (antigen A present, anti-B antibody present, but antigen B absent) and B (antigen B present, antigen A absent), labeled C (both antigens A and B absent), but was relabeled later as O. Then another type of serum was discovered, and this fourth type was labeled AB (both antigens present). The blood type of an individual is greatly affected by his parents’ blood type.
Further, Dr. Leon Lattes of Italy, created blood testing for dried blood sample in fabrics (MacDonell, 1993). As early as 1904, Hans Gross of Germany documented and evaluated bloodstain collection. In 1939, geometric principles had been applied to deduce the angles of impact and convergence of the obtained bloodstain. In London, as early as 1514, blood spatter evidence was used in a court trial (Saferstein, 1995). As early as 1925, blood has been discovered and used for criminal investigation. Almost 80 percent of the human population were “secretors”.
An individual carries specific types of antigens, proteins, antibodies, and enzymes characteristic of their blood that are also present in their body tissue and fluids. In the case of a secretor, investigators can tell the blood type by examining other body liquids such as saliva, teardrops, skin tissue, urine, or semen correlating the blood type obtained from the victim to the criminal. From 1951 hence, Dr. Paul Leland Kirk confirmed the effectiveness of bloodstain pattern interpretation in resolving crimes (Bevel & Gardner, 1997). In 1985, DNA technology made blood analysis easier.
DNA obtained from blood samples at the crime is analyzed within a shorter period of time, comparing it with the blood profile of an individual. The gender and type of criminal can be assessed by analyzing the blood sample obtained from the crime scene. Aside from presence of blood, the way it landed on surfaces gave rise to a new forensic field, blood pattern analysis, telling experts pertinent details about the murder (Bevel & Gardner, 1997). Blood at the Scene of the Crime Benecke & Barksdale (2003) suggest that blood shedding is a dramatic accessory for the execution of a violent murder.
Nearly 9 percent of the weight of a healthy person is blood and if spilled by murderers, it can leave a long trail. As blood is shed off in any volume, clotting makes it difficult to assess. Thus murderers’ attempt to wash off their violent murder often fails because blood traces stick to their clothing and weapons. Blood present at the scene of the crime has lead to the punishment of many killers who initially thought they can get away by removing all their incriminating traces (Benecke & Barksdale, 2003).
Blood is very vital in relation to forensic science, from which much information may be obtained. The first task in analyzing stains is to determine whether there is blood and to whom it belongs. Afterwards, stains are examined for age, sex and blood group. The shape and pattern of liquid blood splashes reconstructs the murder scene. Bloody fingerprints and palm prints tell their own story. A single blood trace can provide much information, and analytical techniques are continuously improving through time.
Blood dynamics is not only used for narrowing suspicion on the guilty party, but also to prove a suspect’s innocence. Bloodstains are reconstructed, eventually allowing investigators to simulate what transpired in the crime scene (Fisher, 2003). Blood investigation at crime laboratories is studied using two different approaches: the biological approach (serology) and the physical approach (blood splatter or bloodstain pattern analysis). The facts obtained from complex blood investigation form the core of blood evidence.
Examination and interpretation of bloodstains on and around the body, and of blood spots, splashes and smears at the scene of the crime, are an essential part of a murder investigation. In addition, the location and the manifestation of blood marks on the body and its immediate surroundings help the investigator reconstruct the crime (Geberth, 1996). Blood is a liquid and hence, the laws of physics can be validly used for interpreting blood spatter. The factors that can help in reconstructing the crime scene include spot size, quantity, shape, distribution, location, angle of impact, and target surface.
Correlating these factors can reduce the long and tedious process of investigation. The shape of blood spots and the position of the victim are correlated; blood vertically dropping on a even surface has a circular mark with crenated edges, indicating that the source was in a still position during that particular time. Drops of blood falling from an object in motion collide with a flat surface diagonally leaves an exclamation-mark-like spot. A thorough analysis of the shape of obliquely falling blood splashes indicates the details about speed and impact.
This information are suggestive of the position of the victim and murderer, and even the weapons used during the crime. Blood spots lined on the ceiling of a room in violent murder cases, such as when the killer wielded an axe, results to lined blood spots on its ceiling (Klug, 2000). Blood smears and trails on the floor can be from a crawling wounded person or a murderer dragging the lifeless body of the victim. Blood smears become ragged at one of its edges telling the direction of the movement that occurred during the crime.
In instances where the blood stain is not evident, tail fingerprints may be obtained. Moreover, invisible blood stains can be detected by doing a luminol test, which shows slight phosphorescent light in the dark where bloodstains (and certain other stains) are present (Geberth, 1996). Colored string is often used at a crime scene to show the path of blood droplets cast off from a knife or object used in a beating. These devices can give investigators a preliminary idea of the location of victim and the perpetrator at the time of the crime.
They become even more important in situations where there is more than one perpetrator, where a victim manages to crawl from one location to another, or has been dragged. However, the definitive interpretation of blood patterns comes when the information is analyzed back at the laboratory using computer programs (Crow, et. al, 1996). Young (1989) indicates that blood pattern analysis includes the examination, identification and interpretation of patterns of bloodstains and relating these to the actions which may have transpired during the crime.
This analysis plays an important role in reconstructing crime events. The bloodstains obtained are indicative of the type of injuries, the order in which the wounds were received, whose blood is present, type of weapon that caused the injuries, whether the victim was in motion or lying still when the injury was inflicted, whether the victim was moved after the injury was inflicted, and how far the blood drops fell before hitting the surface where they were found.
In the 1930s, John Glaister, a Scottish pathologist categorized blood splashes into drops on a horizontal surface; splashes from blood flying through the air and hitting a surface at an angle; and pools around the body, which can show if the body has been dragged (Young, 1989). Bloodstain patterns are a helpful tool for crime scene investigators to understand the integral components of the crime, finding evidence for answering questions about the crime.
Through bloodstain pattern analyses, collecting unecessarily excessive blood may be avoided. The shape of the blood drop itself holds significant information. The proportions of the blood drops can tell the needed energy in those dimensions. The shape of the stain can describe the traveling direction and angle at which it struck the surface (Klug, 2000). Before a scientific investigation of a violent crime is concluded, bloodstain pattern analysis is carried out and makes a noteworthy contribution to the investgation process.
Bloodstain pattern analysis reconstructs the assassination that occurred, specifically the blood shedding. Because blood is uniform, it behaves accordingly. Moreover, the manner through which blood goes in and out of the victim, how it was splattered around the area of the crime, are also important sources of information for reconstructing what truly happened. Blood spatter analysis is based from the disciplines of physics and mathematics, from which the main concepts of blood pattern analysis are derived (Saferstein, 1995).