Police in Illinois, USA have revealed how they use laser scanning to record crime scenes, with the county’s chief prosecutor explaining why the technology carries so much weight in court.
A crime scene rarely stays intact for long. Once evidence has been collected, crime scenes are cleared away and, within hours, life carries on as normal. For the people who must later work out what happened there, that creates an obvious problem: the place they need to understand no longer exists in the form it took on the day.
In Champaign, Illinois, police have spent the past five years working around that problem with a 3D laser scanner. The device records a scene in enough detail that investigators, lawyers and juries can return to it long after the event, sometimes years later, and examine it almost as though they were standing in it.
The department is now upgrading that scanner. Champaign City Council has approved just over $76,000 in federal grant funding for new police equipment, covering a replacement 3D laser scanner along with portable fingerprinting equipment.
Why 3D scanning is the answer
Champaign police first adopted 3D scanning in 2021. Time-of-flight laser scanners send out laser beams that sweeps across surroundings, measuring the distance to every surface it meets. In a matter of minutes, a single scan can record millions of individual points, each one fixed at an exact position in three-dimensional space.
Operators usually set the scanner up in several places around a scene, and software then joins the separate scans into one complete model, often overlaid with color photography so that it closely resembles the real location.
The result is a very different record from a set of photographs. A photograph shows a scene from one fixed angle, and it can be hard to judge from it how far apart two objects were, or what could be seen from a particular spot.
A 3D model can be viewed from any angle, and because every point carries a precise position, distances can be measured directly on screen. Investigators can check where each item of evidence lay in relation to everything around it, and how the wider surroundings, such as doorways, walls and lines of sight, fit into the picture.
Because the model is kept as a digital file, it does not fade, get damaged or change over time. When a case reaches trial months later, prosecutors and defence lawyers can open the same record that investigators made on the day, and if the case is reviewed years afterwards, the scene is still there to be examined again. Questions that nobody thought to ask at the time can still be answered.
Real forensic use cases
The value of this became clear in a case from June 2025, when a 13-year-old was shot in the head in the courtyard of Oakwood Trace Apartments in Champaign.
The scanner had captured the courtyard in full. Julia Rietz, the Champaign County State’s Attorney and the county’s chief prosecutor, demonstrated the model to local broadcaster WICS, showing where spent shell casings had been recovered and how far the person who fired the gun had been standing from the victim.
That distance turned out to be central to the prosecution’s case. In an attempted murder trial, prosecutors must show what the accused intended to do, and intent can be difficult to prove directly. The layout of the scene offered another way in. If the gap between the two people was small, and the shot was aimed at the head, jurors could draw their own conclusions about the purpose behind it.
“So it helps us present a more accurate visual depiction of the scene where an offense took place,” Rietz told Fox Illinois. “If you’re shooting at somebody who’s only this far away from you, at their head, what else are you trying to do other than to kill them?”
The defendant was found guilty of attempted murder and aggravated battery with a firearm, and was sentenced to 50 years in prison.
For Rietz, the main benefit lies in how jurors understand the evidence in front of them. Measurements read out by an expert witness, or a pile of flat photographs passed along the jury box, can leave people struggling to picture a place they have never visited. Testimony alone has the same limitation. A model that they can see from different angles fills in much of what those other forms of evidence leave out.
“We are a very visual society. People want to feel like they are immersed in the situation, especially if it is their job to consider all of the evidence and make a decision beyond a reasonable doubt about whether someone is guilty of a crime as serious as a murder or shooting,” said Rietz.
Upgrading the force’s 3D scanner
The scanner’s usefulness is not confined to the courtroom. Recording a scene by hand, with measuring tapes, sketches and large numbers of photographs, is slow work, and every hour officers spend documenting one location is an hour they are not available for anything else. A scanner captures the whole area at once, so officers do not have to decide in advance which measurements might matter later, and quicker equipment shortens the process further.
Deputy Chief Kevin Olmsted said the newer scanner should allow investigators to record scenes more efficiently, reducing the time officers spend gathering and logging evidence.
“The faster that they can process that scene allows them to get back to actually doing their primary responsibilities quicker,” said Olmsted.
The existing scanner has been in use since 2021 and has begun to show its age. Its performance has dropped off, and its battery has become unreliable, which is a real concern for a device that needs to run for long stretches at a scene. Rather than wait for it to fail, possibly in the middle of an investigation, the department has decided to replace it while it still works.
Rietz expects the new equipment to improve the way evidence is gathered, preserved and eventually shown to jurors, and sees the benefit reaching everyone involved in a case, above all the people who must finally weigh the evidence.
“So I think an upgrade is, again, going to assist the investigators, my office, and most importantly, the jury,” said Rietz.
The same council decision also pays for portable fingerprint equipment, designed for officers to use in the field rather than only back at the station.
Champaign police say both purchases are intended to strengthen the department’s investigative work. Measured against a city budget, the grant is a modest sum, but the Oakwood Trace case shows how much can rest on a single piece of equipment when a scene has long since disappeared and a jury still needs to understand it.
Find out more about 3D scanning in forensics here.
