How accurate are blood spatter analysis?
Conclusions by bloodstain pattern analysts were often erroneous and often contradicted other analysts. On samples with known causes, 11.2% of responses were erroneous. Both semantic differences and contradictory interpretations contributed to errors and disagreements.
Is blood spatter analyst real?
Bloodstain pattern analysts, also known as blood spatter experts, collect and analyze physical evidence—specifically, blood. They are specialists in forensic science and crime scene investigation and examine the location and shape of blood drops, stains, puddles, and pools.
What are some of the flaws or problems in blood spatter analysis?
National studies have concluded that several forensic sciences, such as those focused on blood spatter, bite marks, handwriting, tire tread and footprint impressions, ballistics and arson are unreliable because they are not grounded in scientific research.
What are the limitations of bloodstain pattern analysis?
What are the limitations of the analysis? Limitations of the BPA include the fact that it cannot recreate the entire scenario, as there are unknown variables that analysts cannot account for using scientific methods.
Is Dexter's job realistic?
The hit Showtime series “Dexter” centered on a blood spatter analyst for the Miami Police Department who moonlights as a serial killer. While the show is based on fiction, the job is very real and harder than Dexter makes it seem (probably due to his serial killer instincts).
Is blood spatter analysis a pseudoscience?
In 2009, the National Research Council condemned blood pattern analysis as “more subjective than scientific.” Nothing changed. In 2016, it called for testing of error rates in criminal forensic science.
How important is blood pattern analysis in a criminal investigation?
Bloodstain pattern analysis provides important forensic information about the crime under investigation; it tells what happened. Bloodstain patterns occur in several distinct categories, each revealing a piece of the crime scene puzzle.
What is the forensic value of blood spatter?
To help reconstruct events that caused bloodshed, analysts use the direction and angle of the spatter to establish the areas of convergence (the starting point of the bloodshed) and origin (the estimation of where the victim and suspect were in relation to each other when bloodshed occurred).
What can blood spatter tell us about a crime scene?
Based on the varying sizes and shapes of the blood drops, investigators can often tell what type of weapon caused the spatter, determine the general area where the attack occurred, and track the positions of the victim.
How do you analyze blood spatter?
Bloodstain Pattern AnalysisWhere did the blood come from?What caused the wounds?From what direction was the victim wounded?How were the victim(s) and perpetrator(s) positioned?What movements were made after the bloodshed?How many potential perpetrators were present?More items...
What qualifications does a bloodstain pattern analysis possess?
Minimum pretraining requirements for a bloodstain pattern analysis (BPA) trainee are a bachelor's degree or equivalent in a field of study related to BPA from an accredited college or university; or an associate' degree or equivalent in a field of study related to BPA from an accredited college or university and 2 ...
What does blood stain analysis examine?
Bloodstain pattern analysis seeks to define the facts surrounding an investigation by the use of the physical nature of bloodstains. Bloodstain pattern analysis is the use of the size, shape, and distribution patterns of the bloodstains found at a crime scene to reconstruct the bloodshed event(s).
How much do blood spatter analysts make?
While ZipRecruiter is seeing annual salaries as high as $134,000 and as low as $24,000, the majority of Blood Analyst salaries currently range between $41,000 (25th percentile) to $85,500 (75th percentile) with top earners (90th percentile) making $114,000 annually across the United States.
Is it hard to become a blood spatter analyst?
The organization requires candidates to have at least 100 hours of bloodstain pattern analysis training and 140 hours of study in a related field, such as crime scene investigation or forensic photography. Applicants must also have an associate or bachelor's degree, plus three years of work experience.
How much do bloodstain pattern analysts make a year?
Years of Experience and Salary The U.S. Bureau of Labor Statistics (BLS) reports that forensic science technicians made an average of $61,220 in 2017 and earned a midpoint, or median salary of $57,850. A starting blood spatter analyst salary is around $42,000 a year.
How many years does it take to become a blood spatter analyst?
Education. High school diploma or equivalent and four years of experience in bloodstain pattern analysis equals the Bachelor's Degree requirement.
What is blood spatter analysis?
Blood spatter analysis is the study of blood spatter patterns left behind in a crime scene to recreated the hypothesized events of the crime. The most common finding, is an area of origin in which the blood came from. In other words, where was the victim positioned when he was struck or hit by the weapon that caused the splatter.
Is blood spatter a science?
Despite its popularity in these shows and the countless people affected by “CSI” effect, blood spatter as a science has not been studied very extensively compared to the other disciplines of forensic science. In fact, if one were to do some research, not a lot of reliable literature can be found on it. As if that was not troubling enough, various blood spatter experts cannot seem to agree on the many key issues in blood spatter analysis. The stand on how accurate one can or should measure the origin of blood spatter vary from to the nearest inch to the nearest general direction. More importantly, the techniques used to carry out the analysis also range from crude estimates to expensive computer software. One of the more commonly used technique is stringing, as seen on the television where the crime scene analyst attaches various string to the blood spatters to find on common point of origin. (though in real life it would be more of area of origin) Despite the varying methods, all of them are based on the same elliptical model which makes a few assumptions on how blood travels. A brief explanation on the model can be seen in the diagram below.
Why is blood spatter analysis important?
But more than 1.5 liters and death quickly becomes a risk. 7. Blood spatter analysis can be essential in determining the type of weapon used during a crime. There are many reasons an investigator may not know what type of weapon was used during a violent crime.
What is blood spatter analysis?
This field involves using the physics of fluids to help to determine the events of a (usually) violent crime by analyzing the placement of the blood droplets at the crime scene.
What is BPA analysis?
5. BPA is perhaps most often used to confirm or refute the statements of witnesses or suspects present at the commission of a crime.
What is BPA used for?
5. BPA is perhaps most often used to confirm or refute the statements of witnesses or suspects present at the commission of a crime.
How much blood volume do you lose before you die?
6. A human must lose approximately 40% of his or her total blood volume before they are at risk for death from blood loss.
When was the first blood stain discovered?
Keep reading to learn more. The first modern study of blood stains occurred in 1895.
When was BPA first discovered?
However, the first surviving modern study of BPA occurred in 1895 when Eduard Piotrowski from the University of Krakow published a paper entitled “On the formation, form, direction and spreading of blood stains resulting from blunt trauma at the head”.
Why is blood spatter analysis important?
Blood spatter analysis can be helpful in a number of different ways. It can mostly be used as a way of eliminating possibilities . By itself, it cannot confirm or prove what actually occurred. It is at most an exclusionary tool. However, as currently practiced in the United States today, it is being be used to suggest the kind of injury sustained, the final movements of the victim, and the angle of the shooting or attack.
What are the two types of spatter?
They attempt to subjectively categorize the universe of possibilities of spatter into two different types of spatter: forward spatter and backward spatter. Both types, they say, will be emitted in a conical fashion in that the impact of the projectile will create a path which expands out from the impact site and grow in width as the spatter moves forward as it is projected. Back spatters, they contend, will almost always be possible whereas forward spatter will only occur when an exit wound occurs.
What is the assumption of forensic science?
One of the assumptions made by those who practice this form of forensic science discipline is that in examining the stains, the number of stains found will be dependent on the nature and site of the injury, the presence of any intermediate targets such as clothing, and the nature of the projectile used to cause the wound.
What is blood whisperer?
If you have ever been involved in any sort of homicide case, you will almost always run across the “blood whisperers” which are folks who honestly believe that blood left at a scene can “tell us the story of the crime”. Blood spatter analysis can be helpful in a number of different ways.
How far can blood be carried?
Due the small size of the blood, the blood will only carry 4-5 feet. When shot at a 4 foot range, the gunshot wound could deposit stains on the weapon, shooter’s body and or any clothing involved., Furthermore, the small size of such blood can also cause such stains to be easily overlooked both the by the shooter and by the investigator. ...
Is there a lack of education in the practitioners as to the real science that involves the above?
There is also a lack of education in the practitioners as to the real science that involves the above. They attempt to apply and to interpret the real science based upon that which they objectively see to extrapolate it out to that which they subjectively conclude without the basic understanding of “why”.
Is back spatter bigger than forward spatter?
The back spatter, on the other hand, will be less defined, slightly larger, and have fewer particles. While back spatter is more possible than forward spatter, the presence of back spatter will be partly dependent on the manner and distance at which the weapon is held.
Is scientific evidence more valid than witch trials?
Yep. A lot of "scientific" evidence that makes it into court is no more valid than the witch trial tests. This is America.
Is blood-spatter analysis still used?
I realize this trial was a while ago, and technical crime scene methods were less advanced, but blood-spatter analysis is still used and held up as an accurate method of testing. It's incredibly subjective, like a lot of forensics testing.
Can you use blood splatter in forensics?
IF they found the murder weapon then the blood splatter forensics MUST be compatible with it. So this makes blood splatter analysis easier to get right. Ballistics combined with blood splatter and even without it can give you trajectory, which means a probability of positioning everything in the scene quite well.
Did the murder weapon be found in Blood Splatter?
The problem with the blood splatter forensics here is that the murder weapon was never found and the prosecution went with a poker. That immediately tied down Deaver into using just a poker to get his results. His results look very poor. What does this tell us? That MP didn't use a poker. That's all it tells us. It doesn't tell us an object wasn't used and it doesn't say MP didn't bludgeon her.
Is blood spatter a science?
The problem is that is not a science but it is portrayed by some as if it is. Many cops go on a blood spatter course of just of few hours which is impossible to fail. This is the same course that ‘experts’ attend and use in court.
Can blood splatter forensics be compatible with murder weapons?
IF they found the murder weapon then the blood splatter forensics MUST be compatible with it.
Why are blood stain patterns examined?
The patterns of blood spatter at a crime scene are examined by forensic experts to recreate how the perpetrator committed the crime. Even though scientists have called into question the reliability and validity of blood-stain pattern analysis, it continues to be used by the prosecution.
Can you shed DNA at a crime scene?
As you may know, you, as a normal human being, shed DNA all over the place whenever you touch anything and even when you do nothing. Another person touching the things you touched before he or she can pick up your DNA, and then “drop” it at a crime scene. Guess who will be implicated in the crime when your DNA ends up at the crime scene?
Can forensic analysis be used in prison?
Unfortunately, prosecutors continue to use forensic analysis tools that have been debunked and proven to be ineffective by scientists. Unless your criminal defense lawyer steps in and adopts an aggressive approach to reasonably question the accuracy or admissibility of forensic evidence provided against you, there is a high chance that you could end up in prison.
Is blood stain pattern analysis reliable?
Another popular forensic analysis method called bloodstain pattern analysis is arguably the most unreliable and discredited by the scientific community. You probably know how this technique works from watching episodes of Dexter. The patterns of blood spatter at a crime scene are examined by forensic experts to recreate how the perpetrator committed the crime. Even though scientists have called into question the reliability and validity of blood-stain pattern analysis, it continues to be used by the prosecution.
Fluid Dynamics
Environmental Factors
- BPA analysis is also made less certain by environmental factors at the scene. Humidity levels can have a considerable effect on the drying time of blood droplets. At 60% humidity or greater, drying time is altered considerably[11]and was found to slow “as humidity increased from 12-66.5%”[12]. As such, as the age of the blood droplet increases, eve...
Misidentification and Physiological Factors
- Another issue with BPA is the risk of misidentification. Blood that has been expirated (such as when there is bleeding in the mouth or throat) forms splatter patterns producing a fine mist, which can be misidentified as high-velocity impact spatter[15]. Viscosity and surface tension both factor into how blood acts in flight as well as how a drop spreads or splashes upon impact[16]. Howev…
IAI Requirements
- There is a further concern with the requirements for BPA analysis certification. The IAI only requires a certain number of hours of training to be licensed to do BPA analysis[19]. There is no required testing of forensic investigation skills relating to BPA. This lack of educational requirement seems at odds with the “importance of rigorous and objective hypothesis testing an…