Home Articles Solving ‘who dunnits’ with 3D laser scanners

Solving ‘who dunnits’ with 3D laser scanners

Leica scanstation P20
High-speed laser scanners such as the Leica ScanStation P20, combined with a rolling tripod base and intuitive processing software, allows agencies to quickly scan crash scenes and create accurate documentation for the courtroom

State-of-the-art surveying technology is capturing the attention of criminal justice professionals and revolutionising the science of forensics. By Michael Cunningham

Surveyors and engineers have been using 3D laser scanning to document as-built conditions of structures since the late 1990s. Surveyors, especially, were quick to appreciate the laser scanner’s ability to capture highly accurate measurements of complex environments. Now this state-of-the-art surveying technology is capturing the attention of criminal justice professionals and not only revolutionising forensic investigation but also the way evidence is presented in court.

Advantages on crime and crash scenes
Conventional forensic investigation methods are time-intensive and dependent on a subjective human decision-making process. Photographs are taken. Measurements are made — usually with tape or other manual devices. Drawings and diagrams are sketched. Evidence is documented and collected, and the scene is released. Hours in the field are followed by days or sometimes weeks in the office analysing data and creating exhibits for courtroom use. It is a slow, cumbersome and inexact process.

“When I saw what laser scanning can do, I was completely convinced that this was the way to go for the future,” says Steve Holloway, Deputy Director of the Wyoming Crime Laboratory, which adopted laser scanning technology over two years ago.“It’s a tremendous piece of technology,” says Holloway. “It has so many benefits that it is hard to comprehend them all in a single conversation.”

Speed and accuracy: While investigators can collect perhaps dozens of measurements over the course of an investigation, the latest state-of-the-art laser scanners can capture millions of highly accurate data points in minutes. When combined with fast, easy-to-use software and knowledgeable support, the technology provides a comprehensive solution for quickly documenting and mapping crime and crash scenes.

“I have been a sworn officer now for almost 34 years, and over that amount of time, I have seen very simple crime scenes that take 30 minutes to an hour and you are done with everything that can realistically be done. I have seen crime scenes that we have had to hold on to and work on for weeks,” says Holloway. “But I have never seen a crime scene that, using this technology, could not be completed (as far as all the scanning and capturing of data) in a matter of one, two days at the most — if it was some horrific thing — because it is so fast.”

When one talks about that kind of speed in gathering this data, the amount of time and effort saved is so great that it’s hard to get your mind around how thorough this is and how quickly it’s done.

Objectivity and comprehensive data capture: Experienced crime scene investigators are highly observant and very good at picking up on small clues. Yet even the best investigators cannot measure everything or predict what might become significant after a crime scene has been released and new facts develop. In contrast, a laser scanner is objective, not subjective, about what gets documented, which protects investigators from overlooking key evidence. It impartially and comprehensively captures everything in its line of sight and within its range, even areas surrounding the main crime scene, which may later come into play.

Say, for example, a person unexpectedly comes forward claiming they “saw the whole thing” from a motel room down the street. “Well, you would not have captured that data in your diagrams and measurements of what windows were where in a building down the street that is not involved,” says Holloway. Whereas, this technology, if it was within the range of it, may allow one to turn around and look back and see if they could have seen what they are claiming. That is why this technology is so valuable — it captures everything in the vicinity so that one has that information in the future when something new becomes important that was not anticipated.

Ongoing virtual access to the scene: A bedrock principle of forensic investigation is that you only get one shot at the crime scene. However, if the scene has been laser scanned, it remains pristine forever in a virtual environment. With intuitive visualisation software such as the Leica TruView freeware, investigators and other criminal justice professionals can revisit the as-scanned crime scene to re-analyse and confidently extract survey-quality measurements long after the scene has been released, even decades in the future.

“We need to keep our evidence pristine, and if we have to bring a battery of detectives through a scene just so they can get a feel for the scope of it, we are risking contamination and cross-contamination,” says CSI Section Supervisor Ryan Rezzelle, of the Johnson County Sheriff’s Office Criminalistics Laboratory in Olathe, Kan. “By scanning the crime scene, we can bring the scene to them.”

Laser scanning is taking the science of forensics to a new level. “It is going to affect forensic investigation very much like DNA affected the world of biology,” adds Holloway. “Laser scanning is going to become the gold standard for processing crime scenes across the country in perhaps10 years. It may not even take that long.”

Advantages in the courtroom
Laser scanning technology is also revolutionising the way in which evidence and exhibits are presented in the courtroom. For decades, juries have made life-altering decisions based, in part, on static two-dimensional photography and diagrams. Today, highly accurate 3D visualisation software transforms scan data into an informative, interactive and compelling alternative.

3D visualisation tools can transform scan data into informative, interactive and compelling scene reconstructions

In California, a jury is transported virtually into a vivid 3D crime scene along a rural country road. They are shown undeniable forensic evidence that leads them to convict a known gang member for the assassination of a sheriff’s deputy. In a New Jersey court, a homicide detective uses a single 3D image to utterly destroy the defendant’s claim of self-defense in the killing of his neighbour.

Virtual scene reconstructions such as these are made possible with 3D, 360-degree visualisation software. The software combines panoramic scene photography with millions of data points and acts as a canvas onto which text, measurements, and links to things like scene photos, audio and surveillance video files can be positioned exactly where they were found on the crime scene.

A mock crime scene demonstrates the use of a laser scanner to quickly and accurately capture all the details of the scene

Users can view, pan, zoom, measure and markup the point cloud data over the Web on their Internet browser. If, during the trial, an attorney wants to know the distance from a doorway to a body, the measurement can be instantly displayed in the courtroom on a computer screen. Regardless of what data someone may request, it has all been captured. “So you are not in a situation where somebody says, ‘Gee, we didn’t measure that when we were at the scene’ or ‘It’s approximately this far just based on this scale drawing’,” says Holloway. “We can know exactly. We can pop it up right there on the computer, and it tells you instantly what those measurements are — which might be very critical to supporting or disproving the theory of a crime.”

And with the advent of CSI-based television entertainment, today’s juries expect to see physical evidence that supports the argument the attorneys are making. “It is a question of having an increased reliance on the information being the truth and not being swayed by a possibility argument,” Holloway explains. As a result, lawyers are becoming increasingly reliant on compelling images and scientific 3D animations created with the laser scan data and visualisation software to make their case. It is a powerful way to communicate what really happened at the crime scene.

“One of the best things that we can use this technology for is creating perspective views,” says Rezzelle. “When we are able to display it in both two and three dimensions, you get much more of a feel for the texture of that scene, the placement of items, and the spatial relationship of them to each other.”

Meeting admissibility standards
Despite all the benefits of 3D laser scanning, even the most compelling evidence is useless if it fails to be admitted in court. As any crime scene investigator knows, data must present a fair and accurate representation of the scene to be accepted as evidence. These considerations are especially important in a criminal trial where lives hang in the balance.

Any technologies used on a crime scene must meet the criteria established by the criminal justice system. In the US, for example, guidelines created by the National Forensic Science Technology Center recommend on-the-scene measurements to be accurate to within 0.25 inch, and the accuracy of all measuring devices, including laser scanners, to be ensured by comparison to a measure of certified accuracy such as a National Institute of Standards and Technology (NIST) traceable ruler.

In 2013, Leica Geosystems introduced a new NIST-traceable twin-target pole that definitively validates the accuracy of 3D laser scans captured with the Leica ScanStation P20.

Verifiable accuracy helps ensure that scan data evidence will hold up in court against rules of evidence such as the Daubert Standard which governs the admissibility of expert testimony regarding scientific evidence in US federal legal proceedings. One such ruling took place September 30, 2013. Federal Magistrate Judge Gregory Wormuth, presiding over the US District Court for the District Of New Mexico, issued an order granting a Daubert Motion to affirmatively admit Leica Geosystems ScanStation evidence and related expert testimony in the case of Stephan Cordova vs. City of Albuquerque, et al. “The provable accuracy of 3D laser scanner measurements to a known standard is key to forensic credibility in the courtroom,” says Tony Grissim, Public Safety and Forensic Account Manager, Leica Geosystems.

State-of-the-art 3D laser scanning is quickly becoming the new standard for documenting crime and accident scenes with accuracy, objectivity and fidelity and then presenting those findings in court. With highly accurate scan data and sophisticated 3D visualisation tools, criminal justice professionals and jury members can be confident that justice has, in fact, been served.

Michael Cunningham,
Training and Service Operations
Manager, Leica Geosystems Public Safety Group
Global: https://www.leica-geosystems.com/en/
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