CH115: Science of Crime

Bloodstain pattern analysis is a very useful tool and can provide important information in a case, by providing insight into what type of weapon was used, how many blows, the size of the assailant, and more. There are many scientific aspects of it, and experts in this field are very skilled and go through much training. They use principles of science by looking at the cohesion of drops, angles, distance, and geometric shapes of the blood. 

However, bloodstain analysis can be subjective as different people can interpret the scene in different ways. In the documentary, The Staircase, two qualified bloodstain analysis doctors interpreted the scene differently. The first blood stain analyzer believed that the bloodstain patterns were consistent with that of a beating, however, when Henry Lee reexamined the scene he believed that the bloodstain patterns matched those of an accidental fall. As this type of forensic analysis is purely visual, and interpreted strictly by humans, it leaves room for error. 

It is also difficult to recreate the scene entirely, as there are other factors that cannot be accounted for. For example in the first analysis in the Micheal Peterson case, they tried to recreate the bloodstain pattern using a beating, however, this is difficult to do as there are some variables that cannot be accounted for. The methods are based on the opinion of the expert which can be subjective. 

While blood stain analyzers can provide insight into what may have happened they can also rule out many things they know did not happen which provides investigators with crucial information to narrow down the case. Overall it is inherently scientific, however, there is an area for subjectivity due to bias. Bloodstain pattern analysis is an important tool that should be used however, it should be used alongside other forensic evidence in order to uncover the full truth.

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Bloodstain pattern analysis is vital to modern forensic science. This involves examining the characteristics, locations, and dispersions of bloodstains at a crime scene to recreate events and gather as much information from a scene as possible. Its use in criminal investigations often provides insights into crucial details such as the weapon type, the number of blows, and an assailant’s characteristics and position. However, bloodstain pattern analysis’s scientific validity remains a subject of debate due to a few complexities.
In cases like Michael Peterson’s, documented in The Staircase, a Netflix documentary, two bloodstain pattern analyst experts produced opposing conclusions from the same blood evidence. The prosecution’s expert claimed the bloodstains indicated a brutal beating, while the defense’s expert argued the bloodstains were consistent with an accidental, intoxicated fall. This disparity raises many inquiries into the scientific nature of bloodstain pattern analysis, with the primary concern being the subjectivity involved in the analysis.
Despite reliance on fundamental scientific principles, such as blood behavior/physics, analysts must employ their judgment and expertise for interpretation. This can introduce bias which may affect the objectivity of an expert’s analysis. This bias may stem from training, preconceived notions, legal pressures, or missing an aspect of the blood evidence. Coupling this with the inconsistent terminologies and procedures used within bloodstain pattern analysis further complicates bloodstain analysis. Different experts might use a variety of names for the same bloodstain, highlighting the severe lack of standardization and the potential for inconsistencies and inaccurate conclusions.
However, it’s important to acknowledge that bloodstain pattern analysis is fundamentally scientific. It draws on the principles of many fields of science, some being physics and mathematics, and is observed with many scientific concepts in mind in regards to blood dispersion, and results of impact. In cases where bloodstain pattern analysis is conducted without bias, like the Marilyn Sheppard case when analyzed by Paul L. Kirk, it becomes a powerful tool used to uncover the truth. When executed effectively without biases, bloodstain pattern analysis can accurately uncover a crime’s sequence of events, and in the instance of the Marilyn Sheppard case, exonerated Sam Sheppard.
In conclusion, bloodstain pattern analysis exists at the intersection of science and subjectivity. Subjectivity and bias can be challenges, however, the underlying scientific principles render bloodstain pattern analysis an invaluable forensic tool. Bloodstain pattern analysis should be used in corroboration with other evidence to uncover the full truth about a crime.
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Bloodstain spatter analysis is a forensic method that looks at the shape, size, distribution, and placement of bloodstains in order to reconstruct the scene of a crime. However, numerous research and publications have suggested significant mistake rates and poor consistency. Also, subjective interpretations among bloodstain spatter analysts have called into question the scientific validity of this procedure.

Bloodstain spatter analysis has a number of issues, including a lack of consistent processes, techniques, and validation. The same form of bloodstain may be referred to by several analysts using different names, such as “impact spatter,” “cast-off,” or “arterial spurting.” Additionally, there is no universal agreement on how to categorize, quantify, and interpret bloodstains, which produces inconsistent and incorrect results. Additionally, there is no set standard or benchmark to compare the analyst’s findings with the real occurrences, so there is no easy way to evaluate the precision and dependability of bloodstain spatter analysis.

Bloodstain spatter analysis also has the drawback of primarily relying on the analyst’s individual judgment, experience, knowledge, and presumptions. Based on the information at hand, such as the origin, direction, velocity, and angle of impact of the bloodstains, the analyst must draw a conclusion. However, a number of variables, including the analyst’s training and biases may affect their judgments and conclusions. The analyst might also disregard or miss additional scenarios that could explain the bloodstains.

For example, in The Staircase it is shown how different specialists can draw varied conclusions from the same blood evidence. In this case, the defense expert contended that the bloodstains on the wall and the defendant’s clothing were the result of a fall down the stairs, contrary to the prosecution expert’s assertion that they were consistent with a brutal beating. Both experts supported their opinions with their own expertise and presumptions, but neither offered any unbiased tests to back up their assertions. Therefore, bloodstain spatter analysis is not scientific because it lacks standardized language and methodology and is dependent on the analyst’s subjective assessment. More research is required to develop an objective and quantitative method for bloodstain spatter analysis. (344)

How scientific is bloodstain pattern analysis? Certainly if it’s used in criminal trials it has to have a degree of credibility. Bloodstain pattern analysis or BPA is a subjective forensic science. In episode 5 of The Staircase we can see that the prosecution’s expert claims that the bloodstains in the staircase could have only been caused by a beating. However, in episode 7 the defense’s expert Henry Lee claims that it is impossible for these stains to be caused by a beating and that the only cause for these stains must be from an accidental fall. So if both experts seem to entirely disagree on their conclusions is BPA really scientific? 

Like most observational sciences, BPA is highly subjective. But whether a science is subjective or not, the fact that it still goes through the scientific method is not taken away. BPA uses the chemistry of blood and the physics behind falling liquids to analyze why a scene might look a certain way. Just like in any other science, experiments are done to test the hypothesis of the conclusion that might have been reached. For example in episode 5, the prosecution’s expert tested his hypothesis of how the crime might have happened. He wore a white suit and recreated the crime to analyze whether the bloodstain pattern appeared the same as in the crime. He placed several objects with blood in them and beat them several different ways to see if any of them produced the splatter seen in the scene. In episode 7, Henry Lee also analyzed the blood and tested his hypothesis in front of the jury. He used pieces of cardboard and threw blood at them by coughing on them or just swiping the blood at the cardboard. They both had a scientific analysis of the evidence but I think that the prosecutor’s expert has a bias towards the crime being a beating.

I think the tricky part about BPA is that the analyst might have biases when inspecting the scene and therefore might gear the conclusion to suit this bias. This issue can be overcome by gathering several opinions. But at the end of the day BPA is still science. (364)

                Eyewitness testimonials may be powerful tools in criminal investigations, but they are not the most reliable. Take 9/11 for example, although everyone says that they know where they were when the planes crashed, 40% are wrong. This is thanks to the ‘illusion of truth’ phenomenon, which essentially means our memories tend to believe false truths after repeated exposure. The ‘illusion of truth’ phenomenon is just one way in which our memory can be faulty. When looking at crime cases, there is a high likelihood that the eyewitness makes a false testimony due to aspects that contribute to a warped perception. For example, bias, emotional state, memory decay, suggestibility, and misattribution. This now brings us to the Avery case, a great example of the effects of erroneous eyewitness testimony.

                In 1985 Steven Avery was wrongfully convicted of the rape and attempted murder of Penny Beerntsen. He had spent 18 years incarcerated before his conviction was overturned because of DNA evidence. A key component that led to his conviction was Penny Beerntsen’s faulty testimony. She had recognized Avery as her attacker from a photo lineup and a composite sketch. Her identification, however, happened in a pressure-filled situation after repeatedly having been exposed to Avery’s picture. These all had a great impact on her memory and influenced her false identification.

                Overall, the eyewitness should not have been exposed to Avery’s photo, this greatly tainted her testimony. Furthermore, if the police had followed the correct eyewitness identification procedures, a mistake in identification would have been prevented. For example, the police suggest setting up a lineup with multiple suspects rather than just one suspect. It’s also best to avoid repeating a lineup with the same suspect and the same eyewitness.  Additionally, this procedure should have been recorded and documented on camera. All these methods would have helped to lessen the possibility of a false identification.

My whole life I have enjoyed watching murder shows or movies, where a case is presented and the murder or felon is caught, and it is usually always the right suspect. It was always extremely entertaining to attempt to determine who was guilty and when the case was resolved, a wave of relief would wash over me. I was never previously aware that an individual could be wrongfully accused for such a serious crime. After watching the documentary on Steven Avery, I am completely baffled and concerned for our past and even present justice system. 

Incorrect eyewitness testimonies occur more than one would think. Before knowing this statement, I believed that an eyewitness was the most reliable source in a case because why wouldn’t someone’s real life account be completely accurate, unless they were trying to lie. Turns out I could not have been more wrong. Memory is an odd concept, we as humans tend to be persuaded by outside input as well as connect people or information that is not even related at all. Being in high stress situations when anxiety is surrounding you can often lead to incorrect claims, or one can even jump to conclusions in order to revolve the trauma of, for example, an attack. On top of false accounts by witnesses, bias also plays an important part in an incorrect eyewitness testimony, and that was definitely the case in Steven Avery’s situation.  

It is apparent that this case was unfair from the start as Avery was seen as an outsider to his community. Being somewhat of a troublemaker in his town, stealing a few times, almost running his cousin off the road, and burning a cat, one can make assumptions about Avery’s character. On the other hand, a certain individual was most certainly a contributing factor to Avery’s false arrest. Reserve Deputy Judy Dvorak, who happened to be Avery’s neighbor at the time, strongly disliked Avery. As the victim Penny Beernsten was describing her assailant, Deputy Dvorak mentions that who she is describing sounds like Stephen Avery. Dvorak putting that idea in Beernsten’s head was the start of Beernsten’s false claims and eventually choosing Avery in a lineup.  

Today there are definitely less false arrests and false eyewitness statements due to DNA evidence as well as an adapted lineup system although there are still times when an innocent person is tragically put in jail. 

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