The History of Blood Splatter Evidence in DUI and Criminal Courts
Using Blood stains, blood splatter, and reconstruction evidence involving blood in DUI and Criminal Defense can be very important in showing either innocence or Guilt.
The Pioneer of the scientific use of blood stains was Dr. Eduard Piotrowski from the Institute for Forensic Medicine in Krakow Poland. Piotrowski conducted extensive studies on the distribution of bloodstains relating to head injuries and his work was published in Vienna in 1895. Head injuries being very common in accidents as well as assaults with fist and weapons.
Another early researcher who followed Piotrowski's work was Professor Alexandre Lacassagne (1844-1921). Lacassagne was Professor of Forensic Medicine at the University of Lyons, in France. His work focused on gun shot wounds. Many times it is important in homicide, murder, or assault with a firearm crimes to reconstruct how, at what distance, and where the alleged shooter was positioned. Victor Balthazard and co-workers also conducted research on blood spatter patterns and presented their findings to the scientific community in 1939.
In 1955 during the case of State of Ohio v Samuel Sheppard blood splatter played a large role in showing Shepard was innocent of murdering his wife. Criminalist Paul Kirk presented blood spatter evidence that suggested that a third person was present at the scene (other than Sheppard and the deceased) when the wife was murdered. Sam Sheppard's blood was eventually excluded from the crime scene through DNA tests in 1998. The television show and movie “the Fugitive” is based on the events surrounding this case.
The most referenced and acknowledged work on bloodstain interpretation was conducted by Herbert Leon MacDonnell. Macdonnell researched blood splatter for many years including documents relating to blood spatter interpretation that reached back into the 1500's.
Most of the work by Macdonnell occurred in the 1970's, funded by the Law Enforcement Assistance administration. His two main publications on flight characteristics and bloodstain interpretation are still widely used.
Crime Scene Reconstruction- Criminal Defense and Prosecution cases often rely on crime scene reconstruction evidence to show what they believe occurred. Analysis and reconstruction of a crime scene that links a series of logical scientific explanations as a means to understanding the sequence of events that occurred at that scene as the events unfolded. This process involves proposing, testing and evaluating connections among the physical evidence related to the events, and trying to determine the best explanation of the events that occurred.
Bloodstains can be more important in reconstructing events and solving a case than the use of blood grouping. Such a scenario might occur when a defendant doesn't deny having contact with a victim. A fundamental understanding of all areas of forensic science & experience evaluating crime scenes, investigators can use bloodstain pattern analysis to reconstruct events surrounding a given incident. Stains and patterns need to be documented and recorded before blood evidence is collected.
Bloodstain evidence can help crime scene reconstruction in several different ways:
- By determining the direction of travel of the blood droplets
- By determining the distance from the blood source to the target surface
- By providing information on the angle of impact of the bloodstain
- The nature of the type of blood droplets
- Establishing blood trails, their direction, and speed of motion
- Determining the type of force used to cause bloodshed
- Establishing the type of object used to cause bloodshed, how many blows occurred and the location of the victim during the events
- Establishing a sequence of events associated with the bloodshed
- Through the interpretation of contact and transfer patterns
- Through the determination of timelines associated with the events and the volume of bloodshed
Approaches to Crime Scene Reconstruction-Reconstruction of a crime scene involves at least three approaches:
- Solving the crime or determining the sequence of events though the graphic reconstruction of a series of events
- Applying techniques to reconstruct individual events
- Conducting experiments to reproduce characteristics of bloodstain patterns
There are both subjective and objective approaches to blood pattern identification.
Subjective analysis: Investigators develop a crime scenario based on witness reports, their previous crime scene experience, and other evidence reports. Bloodstains are not used in the identification process and the validity of patterns is not assessed from the observed bloodstain characteristics
Objective Analysis: This type of analysis, which is the preferred method, identifies evidence on the basis of the characteristics of the bloodstains themselves. Identification is not linked to other evidence until the blood patterns are identified.
When blood is shed at a crime scene an event timeline can often be developed that estimates when the blood source was exposed, and when the blood was distributed in relation to when the crime scene was discovered.
Source Exposure- A blood source can be exposed through arterial breach or a physical impact. The amount of blood and pattern of blood can indicate the timeline of events. In determining a series of events, the more blood there is exposed then the longer the time since the onset of the assault. Transfer patterns only occur after a blood source has been exposed but must occur before blood has fully clotted and still available for distribution. The color of a bloodstain can also give an indication of how old the stain is and how much time has passed since the blood was shed. By being able to determine the direction of travel of a stain we can use that information to reconstruct the direction of travel of the victim or assailant after blood is shed.
A crime scene may lie undiscovered for substantial period of time, blood volume may be used to determine how long the victim remained in a specific location, and indicate whether or not the body was moved. Patterns may arise from blood clotting, drying of stains and blood distribution by flies and other insects as well as mixing with environmental factors such as dirt, water, and debris. Transfer and contamination can also add to establishing a timeline of events; overlaying stains and imprints made from footwear made over dry or partially dry stains can also shed light on timing and sequence of events.
The major bloodstain pattern groups are most often linked to a second pattern group. For example an impact spatter will occur at the beginning of an event, but may be followed by secondary cast-off stains shortly thereafter. Reconstruction and scenario development must be reviewed and checked consistently in an effort to remain objective when interpreting the information. A recommended process includes:
- Identifying patterns
- Sequencing them in relation to other patterns (timeline development)
- Comparison with other physical evidence
- Development of possible scenarios
- Testing and eliminating impossible scenarios
- Limiting conclusion to facts that are confirmed or cannot be excluded
Limitations- Although a scenario can be developed to fit the patterns of all the bloodstains identified at a crime scene, it should always be acknowledged that different scenarios could also result in some or all of the observed stains. As more bloodstain patterns are identified and corroborated, then the greater the number of alternative reconstructions and scenarios that can be excluded.
Reconstruction Techniques- Each major bloodstain pattern category can provide info that may help define a crime scene reconstruction. This means every pattern observed at a crime scene needs to be evaluated and applied to reconstructing the events that may have occurred. Methods and processes for evaluation and application are being improved as technology progresses. To reconstruct the origin of a bloodstain, string or laser reconstruction, or computer analysis, can be used. Many technical investigators prefer computer applications for analysis since it speeds the applications and potentially reduces human error. When conducting cast off reenactments during a reconstruction process, it is very important to use a weapon that mimics the crime scene weapon as closely as possible. The benefits of reenactment are lost if the dynamics don't bear any relation to the alleged crime.
Technological developments won't always represent the events accurately. For example, arterial spray patterns may be demonstrated using a blood filled syringe, needle, or pump. Although these devices are useful they do not accurately mimic the nature of arterial spurting. A pump will make periodic spurts while a damaged artery will consistently pump blood under pressure with periodic surges.
Due to safety considerations and general lack of availability, human blood is rarely used in crime scene reconstructions and is often substituted with ink, paint, glycerol and red dye, dyed salt water, and animal bloods. However none of these behave in exactly the same way as human blood.
Each type of bloodstain pattern and some issues of reconstruction will be addressed in more depth as the course progresses. Before moving onto the flight dynamics of bloodstains, impact and drop formation in the next module it is important to define the terms and nomenclature associated with blood spatter patterns and their interpretation.