Using Testimonial Evidence as “Data” in Crime Scene Reconstruction
A recent hearing I attended raised an issue regarding crime scene reconstruction, thus I’m going to shift gears from BPA for a moment and discuss this issue. It is near and dear to my heart and involves the use of testimonial evidence as “data” in a crime scene reconstruction.
In the hearing, I presented my CSR conclusions, which were minimal. The analysis supported both attorneys’ positions and thus was not particularly probative. After direct, opposing counsel began their cross and followed this line:
Q: Mr. Gardner did you have the trial transcripts available to you?
Q: Were you aware that there was an eyewitness?
A: Yes sir.
Q: Did you incorporate that eyewitness testimony into your CSR effort?
A: No sir, I look at the testimonial evidence only after I have completed the primary CSR effort.
Q: (With great bravado and tonal inflection while looking at the Judge) So you didn’t think it was important to incorporate the eye-witness account into your analysis?
A: No sir, the whole function of CSR is to define objective information, which can then be used to decide if we can corroborate or refute the more subjective evidence, which includes the testimonial evidence.
Q: (Ignoring the answer, counsel repeats the prior question, with the obvious innuendo that I had screwed up)
So lets start by defining what crime scene reconstruction is. A CSR attempts to define objective actions by various parties that are occurring during an incident. Whenever possible it defines the order of those actions. The data used to define these actions include the physical artifacts, scene context and any forensics that may be forthcoming. These actions are always based on hard data and preferably with as little inference as is possible.
As Ludwig Benner pointed out some years ago, the product of this analysis is effective for providing an objective foundation on which to test the more subjective aspects of the investigation, including the testimonial evidence.
Testimonial evidence is and always has been a major issue in any criminal investigation. The criminal justice system and the criminal investigator are constantly trying to answer the question: What, if anything, should we believe from the various witnesses and participants? As far back as 1898, Hans Gross warned investigators that if they piled testimony upon testimony, they would be led from the truth. That concern hasn’t changed and it is not singularly an issue of people purposefully misleading us. The human brain and our sensory skills are a phenomenal machine for the observation of our environment. But as phenomenal as it is, it is also highly flawed. Our brain takes shortcuts, fills in sensory information and gets things wrong all the time. If you've never seen the National Geographic show Brain Games, I would suggest you watch it. It is enlightening from an investigator’s perspective. Regardless, every good criminal investigator learns from the start of their career that testimonial evidence is often flawed for a variety of reasons.
That it may be flawed is an obvious concern for the analyst, but there is another consideration. The product of the CSR is used to test the testimonial evidence; logically we cannot use that which we are testing, as the means of testing.
The bottom line is that testimony should not be true “data” in a CSR mindset. As we’ll discuss that doesn’t mean it isn’t important, but it cannot be the data that specific CSR actions are based upon. Consider a simple example:
Imagine a room where a victim receives a penetrating gunshot wound to the chest. The victim collapsed on the floor near a north wall, blood pooling around them. The victim’s left hand is bloody. On a south wall, approximately 7 feet from the victim is a swipe mark in the victim’s blood. The swipe mark is shoulder height on the wall and indicates a swiping motion left to right and slightly downward. There are no other bloodstains or evidence present that would allow one to connect the dots between the victim’s position and this swipe.
In that circumstance, the CSR analyst would likely define the action on the south wall as “Blood from the victim was deposited on the south wall, left to right, sometime subsequent to injury”.
We know it happened, but from a CSR perspective it is ambiguous in terms of how. Was it a function of the victim’s action? Was it created by the suspect’s activity? Was it a post-incident artifact created by EMS? Given the limited data, any one of these potential explanations might be valid. But lacking hard data, the analyst cannot assume one over another.
Now let’s interject an eyewitness. The eyewitness reports that the victim was present near the south wall when they were shot. The victim remained standing a moment, placed his left hand to his chest, and then placed his now bloody hand on the south wall for support. The victim then stumbled forward, collapsing to their final position.
Under those circumstances what was ambiguous (e.g., Blood was deposited) is now understood. As an analyst we have an immediate and valid explanation of how the swipe pattern came to be on the wall. The jury or analyst would look at such testimony and go “Absolutely, that makes complete sense”. But the actual situation from a data perspective has not changed. If we insert the testimony as the “data” and change the CSR conclusion to “Victim touched the wall and deposited the blood” we have introduced an act of confirmation bias. We are taking the testimony on faith and fitting the limited evidence we have to that explanation. No new hard data exists that affords the analyst the ability to say how that blood was deposited with certainty.
Without a doubt, in the context of a statement, the analyst may better understand a scene. A CSR effort often identifies that certain things are occurring, but will be unable to answer specifically how or perhaps when they occurred. In the context of testimony (admissions, confessions, eyewitnesses) placement of those actions in the CSR become clearer in the broader perspective. Using the old puzzle analogy, the pieces start to fit! But once again, the conclusions arising directly from the CSR have not changed. As the hard data has not changed, to remain objective the CSR conclusions themselves must remain ambiguous. Knowing something and believing something are two very different things. To some this is perhaps a minor nuance, but it is significant in its effect. What if the testimony is wrong, what if they are lying?
This consideration that testimony is not true data, in no way limits the analyst. Given this broader understanding based on the testimonial evidence, the analyst can still share this knowledge. One of the most effective ways is for the attorney to present the issue as a hypothetical:
Q: “Given a hypothetical situation in which a, b, c and d occurred, is your scene analysis consistent with such a circumstance?”
A: “Yes and in fact those circumstances would explain and help us understand why we saw the evidence of actions x, y, and z”.
And of course a simpler approach is:
Q: “Mr. X testified that … , did your analysis find anything inconsistent with that testimony?”
So believing the testimony and expressing how it assisted the analyst in understanding the scene in the broader perspective is not lost. We are simply recognizing that the cart must follow the horse – we believe the testimony, because the CSR conclusions support it and if true the testimony provides an explanation for the more ambiguous aspects of the CSR analysis itself.
There is one major exception to using testimony as data. If we are presented with a witness, who had the ability to observe and actually took note of some scene condition that was subsequently altered or is now in question, so long as the witness is generally free of agenda such information can and should be used.
I realize that some analysts believe in interjecting testimonial evidence into the analysis. I hope I have demonstrated why A) It is unwise and B) Why it is unnecessary. Whatever choices you make in your CSR efforts, always approach testimonial evidence cautiously. Never forget Gross’ admonition, as he was absolutely correct.