The Numbers Don’t Lie
Written 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 revolutionizing forensic investigation but also the way evidence is presented in court.

Laser Scanning Surpasses Conventional Forensic Methods

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 analyzing 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,” said Steve Holloway, deputy director of the Wyoming Crime Laboratory, which adopted laser scanning technology more than two years ago. “It is a tremendous piece of technology. It has so many benefits that it is hard to comprehend them all in a single conversation.”

Fast & Accurate

While investigators can collect perhaps dozens of measurements over the course of an investigation, a laser scanner captures millions of highly accurate data points in minutes.

“I’ve 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’re done with everything that can realistically be done. I’ve seen crime scenes that we have had to hold onto and work on for weeks,” Holloway said. “But I have never seen a crime scene that, using this technology, couldn’t 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 you are talking about that kind of speed in gathering this data, the amount of time and effort you save is so great that it’s hard to get your mind around how thorough this is and how quickly it’s done.”

Objective and Comprehensive

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 about what gets documented, protecting 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 that may later come into play.

Say, for example, that a person unexpectedly comes forward claiming they “saw the whole thing” from a motel room down the street. “Well, you wouldn’t have captured that data in your diagrams and measurements of what windows were where in a building down the street that’s not involved,” Holloway said. “Whereas, with this technology, if it was within the range of it, may allow you to turn around and look back and see if they could have seen what they are claiming.

“That’s why this technology is so valuable: It captures everything in the vicinity so that you have that information in the future when something new becomes important that you hadn’t anticipated.”

Virtual and Permanent

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. As a result, investigators and other criminal justice professionals can revisit the as-scanned crime scene to re-analyze and confidently extract survey-quality measurements long after the scene has been released… even decades in the future.

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

3D Visualization Software Enables Juries to Make Informed Decisions

Laser-scanning technology is also revolutionizing the way evidence and exhibits are presented in the courtroom.

For decades, juries have made life-altering decisions based, in part, on static, two-dimensional photographs and diagrams. Today, highly accurate 3D visualization software transforms scan data into an informative, interactive, and compelling alternative.

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

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

Users can view, pan, zoom, measure, and mark up 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’re not in a situation where somebody says, ‘Gee, we didn’t measure that when we were at the scene,’ or, ‘It is approximately this far just based on this scale drawing,’” Holloway said. “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. As a result, lawyers are becoming increasingly reliant on compelling images and scientific 3D animations created with the laser-scan data and visualization software to make their case. It is a powerful way to communicate what really happened at the crime scene.

Verifiable Accuracy Ensures Admissibility in Court

But 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 in order to be accepted as evidence. These considerations are especially important in a criminal trial where lives hang in the balance.

As a result, 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.

Recognizing this importance for accuracy, 3D laser-scanning manufacturers are working to introduce verifiable accuracy for their equipment. For example, in 2013, Leica Geosystems introduced a NIST-traceable twin-target pole that definitively validates the accuracy of 3D laser scans captured with the Leica ScanStation PS20. The validation tool was developed through collaboration with NIST and is designed specifically to help forensic labs and investigators comply with ASCLD and ISO 17020 and ISO 17025 accreditation standards.

“It’s the 3D laser-scanning equivalent of introducing a scale into a crime scene photograph to provide a control,” said Tony Grissim, Leica Geosystems public safety and forensic account manager.
Verifiable accuracy helps ensure that scan data evidence will hold up in court against the Daubert standard, a rule of evidence regarding the admissibility of expert testimony on scientific evidence in federal legal proceedings.

One such ruling took place September 30, 2013. Federal Magistrate Judge Gregory Wormuth, presiding over the U.S 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 v. City of Albuquerque, et al.

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 3D visualization tools, criminal justice professionals and jury members can be confident that justice has, in fact, been served.

About the Author

After a 26-year career, Mike Cunningham retired from the New York City Police Department in 2012 as a Detective 1st Grade and the senior ranking investigator in the crime scene unit. He was a forensics instructor for the NYPD, is a certified instructor for Department of Homeland Security courses, and served as an international police instructor for the U.S. State Department. Cunningham served his country for ten months at Ground Zero in the aftermath of September 11th. An IAI Certified Crime Scene Investigator and a New York State Certified Police Instructor, Cunningham serves as training and service operations manager for the Leica Geosystems Inc. Public Safety Group. Additional articles by Cunningham can be found in the Leica Geosystems Ready Room at:

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