Charlie Kirk, 31-year-old founder of the conservative nonprofit organization Turning Point USA, was shot on Wednesday while speaking outdoors at Utah Valley University. He was pronounced dead later that day. Officials say the single shot may have been fired from a nearby rooftop. On Friday morning, with a massive manhunt still underway, President Donald Trump has announced that a suspect is in custody.
Crime scenes can change quickly. Chairs, tables, cars—whatever was in the space—may be moved, or people may lose track of them. And future discoveries about the crime may be difficult to connect to the scene. One of the best ways to immediately preserve a crime scene is with three-dimensional laser scans, which use light to map every object present. Today this technique is routinely used at major crime scenes. And experts say it’s likely to be important in the investigation of Kirk’s death.
Among the first crime scene investigators to use this technique in the early 2000s was Michael Haag, a shooting‑incident reconstructionist and co‑author of the textbook Shooting Incident Reconstruction. After majoring in chemistry and minoring in mathematics and physics at the University of Arizona, Haag spent nearly 25 years at New Mexico’s Albuquerque Police Department, where he worked as a forensic scientist on a team that handled major crime scenes ranging from homicides to officer-involved shootings. He also now owns a private company that conducts many of the same services and provides training in shooting incident reconstruction worldwide.
On supporting science journalism
If you’re enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
For more than two decades, Haag has worked on complex cases, taught investigators across the U.S. and testified in court on how 3D laser scans of crime scenes can be used. In a conversation with Scientific American, he explained how this technique would likely be used on the scene linked to Kirk’s death. In plain language, he walked us through how a laser scanner captures millions of measurements to map rooftops and sightlines and how trajectory analysis checks whether impacts line up with a single shooter location.
[An edited transcript of the interview follows.]
Can you walk me through every step of what 3D laser scanning of a crime scene looks like and how you use that information afterward?
The first thing to keep in mind is that, with 3D laser scanning, the massive benefit is that you’re documenting the spatial relationships of everything within that scene very accurately in three dimensions. This allows you to go back and work that scene over and over again. You can look at measurements, angles and distances—anything that has to do with physical measurement and relationships, you can redo. It’s a great tool for everybody involved in a prosecution or civil action.
It’s an engineering tool that we’ve been using in crime scenes since about 2004. These scanners were initially designed to make very accurate measurements of construction sites, factories and bridges. It’s like a laser range finder but much more capable. A handheld laser range finder shoots out a “bullet” of light and, because light moves at a predictable speed, it measures the time it takes for the reflection to return and gives you a distance.
A 3D laser scanner puts that same range-finding device on a stable tripod platform that rotates 360 degrees horizontally and also moves vertically. With today’s scanners, like the Leica RTC that I use, it’s literally shooting out millions of these bullets of light in a very short time frame. It’s not only getting the distance but also associating that distance with a very specific horizontal and vertical angle. From any one position, you build this three-dimensional world around you that is very accurate—we’re talking data points with about three millimeters of accuracy within 20 meters of the scanner.
You then move the scanner from position to position, each time building a three-dimensional sphere of data points, and then you blend all these spheres together. You get a massive dataset. With a scene like this, with a courtyard, multiple buildings and rooftops, you can build a scene that you can fly people through to show a judge, a jury or investigators exactly where all of these buildings are, what the distances are and what trajectories may or may not be possible.
For example, I’ve done a lot of work on the Kennedy assassination and have scanned Dealey Plaza [the Dallas, Tex., site of President John F. Kennedy’s assassination on November 22, 1963]. You can very quickly put yourself in any position you want in that scene and look at what trajectories are or are not possible. That’s exactly what the 3D laser scanner brings to the Charlie Kirk shooting. The challenge is: it depends on where the bullet went after it hit Mr. Kirk. We’ll see whether the bullet … went on to hit something else downrange.
When you said earlier that you could “fly people through” the 3D reconstruction, what does that mean? Do they put on a virtual reality headset? How does someone experience this?
You could use VR headsets, but more commonly, you just put it up on a big computer screen. It’s literally like a computer game where you can get up in the sky and fly down through the scene. You can put yourself above buildings looking directly down. You can put yourself behind windows in buildings looking out into the courtyard. You could put yourself in Mr. Kirk’s position and look out to see what he would have seen. It really allows you to move your viewpoint anywhere you want in the scan data.
In this situation, where people have video footage of a shooter and they know the basics, what would this 3D scan add? How would it be used once they have it?
If it turns out that some of the video we’ve seen of a human-shaped form on top of the building is a viable shooting position, it may most commonly be used to put you in the position of that shooter so you can see what that vantage point would look like—and vice versa, from Mr. Kirk’s position looking uprange.
This scene, in some ways, is not nearly as complex as other shootings we commonly work on where you’ve got multiple shots fired from multiple guns in multiple positions. In those scenarios, the 3D laser scan has more potential to illuminate how the shooting went down, especially when things are moving within the scene.
What other uses could the 3D construction have?
Preserving that scene for the future is the way that comes to mind. This is going to be a shooting that people are going to think about, look at and reevaluate for years to come. Those 3D laser scan data allows people like me and others who just have an interest in the case to revisit the scene in exactly the condition it is today—where the pop-up awning was over Mr. Kirk, where chairs were, where barricades were. Those data will allow us to go back and look at the scene over and over again.
This is just a hypothetical question: A firearm was recovered near the site of the Kirk shooting. If the recovered bullet was shown not to have come from that firearm, could we look at this 3D data and the footage to see where the bullet actually came from? Is there a way to determine exactly what the trajectory was?
Probably not as accurately as you might expect from TV. Let’s take the firearm and [the footage of a] potential figure on [a nearby] roof out of the picture. If we look at the gunshot wound to Mr. Kirk, and we have video that shows his orientation and general body positioning, it looks like a neck shot to me. Let’s say we get a medical examiner’s report that says the entry is the front left area of the neck, and the gunshot wound’s path is from front to back, from left to right and slightly downward, anatomically. If we look at that path, we can start to look at where in that scene the bullet would have come from. In the example I just went through—front to back, left to right and downward—that would include somebody shooting him from his left as he’s sitting in the scene, off in the distance, on top of a building over there. Again, it’s not down to the degree that you might expect from TV, where crime scene investigators put a laser in and say the gun was right along this laser beam. There’s usually about plus or minus five degrees of accuracy, even on a good trajectory with gunshot wounds to bodies. It’s a little bit more conservative than that, but you can get a general idea of where it would have come from.
