Bring Your Crime Scene to Life With 3D Scanning

It is tempting to consider a homicide investigation complete when the handcuffs go on the suspected perpetrator. In reality, this is just the beginning. Of far greater consequence is identifying and establishing the facts of the case; in other words, what is the truth of the matter? Investigators must avail themselves of all the tools at their disposal for identifying and interpreting the facts so they may arrive, to the best of their ability, at the truth. Convictions. Justice. Accountability. All of these are subservient to the truth; truth is built upon fact; fact is supported by evidence.

A tool that is becoming much more commonplace in the quest to document and preserve evidence in its context is the 3D scanner. In the rapidly evolving world of technology, “3D scanner” may be too narrow of a term. Names such as Leica, FARO, Z & F and Riegl are commonplace in the laser scanning community. Matterport and L-Tron provide specialized camera systems for 3D capture; companies like GRADD (Global Robotic and Drone Deployment) train investigators to use ground and aerial-based cameras to produce 3D models and point clouds. A variety of software suites like Pix4D and Reality Capture may be used to convert photographs into stunning 3D views. Speed, accuracy and visualization are the name of the game. Amid all the clamor and excitement of new and improved technology, however, it behooves the investigator to take a moment and asked the question, “Of what value and for what purpose is the data being collected?” In other words, how does 3D scanning help the investigator document evidence, interpret fact and discover truth?

Enhancing the crime scene through 3D imaging can provide solid evidentiary value to the investigation.

Documentation of evidence

Much of crime scene work is identifying, documenting and collecting evidence. Evidence is not always a physical object or property that may be documented and collected. The absence of something can be powerful evidence. When documenting evidence (or the lack thereof), the investigator should ensure the process is thorough and complete. Photography is standard practice and an indispensable aspect of an investigation. In major investigations, such as homicides, it is also important to consider spatial relationships.

Diagramming a scene is made easier through scanning technology.

In times past, when an investigation required a diagram, field sketches were often scribbled in one’s notes, and a variety of measurements were taken to memorialize the scene and its evidence. By necessity a certain amount of subjectivity was introduced since it was beyond the capabilities and time of most investigators to accurately capture the entire scene. Decisions had to be made on what was important and what was not. Often, this process was determined by information known or learned at the time. Experienced investigators learned quickly that what may be learned at the outset of an investigation is often a pale shadow of what actually occurred. “Facts” are often updated, discarded or learned at all points along the investigation.

Sometimes, long after a scene is released, new information is learned which would have changed the way an investigator initially documented the scene. In an effort to adequately and reasonably document a scene, some details may not have been documented which later prove important to the case. A 3D scanner is an objective collector of data. It makes no decisions as to what should be collected or disregarded. It has limitations, to be sure, but decision and discernment are not among them. On normal, full-capture settings, a scanner will collect all data within its field-of-view, density and distance parameters. Though the operator may elect to limit some aspects of data capture, the documentation process is much more objective than manual measurements. It is not uncommon for 3D scanners to collect data on scene which proves useful at a later date.

Intricate details are easy to view with the 3D technology GRADD system.

It is one thing to objectively collect vast amounts of data on a scene, but altogether different when it comes to such things as accuracy, speed and volume. What good is inaccurate data? Striving against accuracy is the reality of time: a limited commodity for investigators. The amount of data collected (volume) is a third prong competing for preeminence. These three elements should be balanced, and technology is making this possible. 3D laser scanners are accurate to millimeters. These highly accurate scans can take less than two minutes to capture. The ability, in some cases, to collect over one million points per second answers the need for volume. Scans and high-quality images are captured in a fraction of the time it used to take with the scanners of yesterday. The result? Investigators can collect accurate data faster and still allow for enough setups to fill gaps in the point cloud.

Not only do these systems provide objective and balanced data capture, they are becoming ever more portable. Laser scanners, once essentially restricted to cumbersome elements attached to large tripods, are becoming smaller and faster. Investigators can opt to use the more robust scanners; smaller, more portable scanners or even handheld, mobile units.

Interpretation of evidence

The laser dots show the measurement between the bullet hole and the blood spot on the victim.

After the data has been collected, next comes the task of interpretation. Endless streams of data do little to inform the investigator of what actually happened. Evidence, like puzzle pieces, must fit together to form a clear picture. Many of the pieces of this proverbial puzzle have be irrecoverably lost. This means the investigator must deal with a very real fact: not everything may be known. Evidence may be destroyed, lost or incomplete. Regardless, it is the task of the investigator to strive to understand evidence in its context. Context. A small word occupying a crucial place within an investigation. Only something observed and interpreted in its context is of use to the investigator. Without context, evidence is vastly malleable. Context, however, provides rules and parameters, an anchor to reality and understanding.

The laser measurements in the GRADD software have an accuracy of 1mm.

Considerations for the interpretation of evidence may include the location and identification of probative evidence; interrelationships between items of evidence; positions and orientation of evidence; and providing macro and micro views of the scene and its parts. How does 3D capture assist in this process? Diagrams are a staple for any major case presentation, and there is no better way to prepare an accurate diagram than using 3D data from a scene. 3D data facilitates tremendous accuracy and details in a series of scene diagrams. Within a good diagram, spatial relationships and evidence location and identification may be addressed. Trustworthy 3D data allows the investigator to view the scene from multiple viewpoints and analyze potential interrelationships between evidence on scene. Furthermore, various measurements can be taken to quantify these relationships (i.e. distances, angles, elevations, etc.). Witness viewpoints and perspectives of the virtual scene can allow the Analyst and Tryers of Fact to see what importance may be attached to the position and orientation of evidence with regard to the scene or other evidence. Diagrams and snap shots from the 3D data provide views of both the big picture (macro) and the detailed parts (micro). The ready availability of 3D data makes this possible far beyond traditional systems of measurement.

Discovering the truth

The goal of any investigator should be finding the truth. Investigations are not opportunities to grind a particular axe or arbitrate comeuppance. Investigators are neither judge nor jury, rather they are to be objective purveyors of evidence, fact and truth. A mindful investigator relies on the facts to point him/her to what actually happened. 3D data allows the investigator to virtually return to a scene at his/her discretion and leisure without the hassle of obtaining new warrants or dealing with an altered scene.

The ability to view the scene from varying viewpoints corresponding to witness statements, victim accounts and suspect testimony gives the investigator an opportunity to compare the evidence with the different (or differing) statements. Could a witness have seen what transpired from their vantage point? How was the victim oriented when the crime was committed? Could the suspect have interacted with the scene in ways that contradict or support his/her account? 3D data provides many opportunities for such comparison.

3D scanning images bring the crime scene to the court room.

Having the scene in a virtual format may allow the trained investigator to reconstruct certain (or sometimes all) of the events which occurred. Investigators should strive for reconstruction. The scientific method combined with the rich 3D data may allow an investigator to put the puzzle pieces back together to reveal a clear and compelling picture. Statements and accounts may be proven or disproven. This all allows the investigator to perform due diligence in the quest for the truth.

How do the various elements and methods of 3D capture help in major investigations? Much in every way. Distilled to three main thoughts, the capture of 3D data allows for the documentation of evidence, the interpretation of fact and, ultimately, the discovery of truth. These elements can combine into powerful demonstratives providing the Tryer of Fact a clear picture of what may or may not have happened. 3D capture is here to stay and may be predicted to become more commonplace. How will it benefit your investigations?