Crash and Crime Scene Diagrams Are Obsolete – Right?

Investigators today are being bombarded with talk of point clouds, fly-throughs, animations, orthrectified images, and simulations. Since a crash or crime scene can just be “scanned” and recorded as a point cloud, some sales people will say that’s all an investigator needs to present in court. Just present the jury with a fly-through of the point cloud or show them a simulation and there is no need to create those old-fashioned diagrams any longer, right?


Accurate diagrams are always an important part of any crash or crime scene investigation. Good diagrams of a scene, based on the measurements, help the jury visualize how the scene looked and where all the important objects and evidence were located. In fact, the diagram in a prosecution can be considered a piece of discoverable evidence that must be provided to the opposing attorney. Having precise diagrams can also help the investigating officer give a more confident testimony in court.

Having an accurate diagrams is critical to use in forensic analysis.

Having an accurate diagram is critical to use in forensic analysis.

According to Sergeant Brandel of the Decatur Police Department (Illinois), “It’s important to have high-quality diagrams. It helps the jury to have a better understanding of the scene and the relationship of evidence to the crime. Juries expect detailed physical evidence to be presented from crime scenes. Part of the responsibility to meet their expectations is to provide good-quality diagrams.”(1)

While point clouds offer an impressive snapshot in time, most investigators wonder if is not enough to convince a jury. Bobby Jones, a law enforcement officer and crash reconstructionist in Tennessee for more than 25 years, explains, “Most jurors have little idea what they are looking at when viewing a point cloud alone. The addition of diagrams to accompany point cloud data assists the viewer in a more complete understanding of all the evidence. Diagrams are the only way to illustrate the complex mechanisms of a forensic analysis such as vectors, momentum, time/distance, blood spatter or bullet trajectories, to mention a few.”

In an article published on, Jon Priest, president of the Association for Crime Scene Reconstruction emphasizes the importance of diagrams: “It (the diagram) becomes discoverable because it is something that the defense can use to support or refute what it is they’re arguing, so accuracy is key. The better your equipment, the better your training and skill level, the less likely there will be errors that will present problems for your diagram. If you make a mistake, it will continue on through the various documentation levels, whether it’s a diagram or something else.” (2)

3D Diagrams Contribute to Understanding

As software for 3D diagramming and modeling has become easier to use, investigators are now able to create their own 3D diagrams for court cases. This type of diagram used to only be seen in high-profile cases where a great deal of money could be used to pay an engineering firm to create it.

Steven Petersen, Criminalist for the Canyon County Sheriff’s Office Forensic Services believes that the ability to present jurors with a 3-D diagram is invaluable.  “It gives the jury a better understanding of what’s there (in the crime scene),” Petersen said. “It can show the entire scene all in one picture. And you can walk people through it not necessarily where a suspect or the victim moved, but as they were physically there in the scene where the doors and walls are and where certain critical items of evidence would be.”

For 20 years, users of The Crash Zone, The Crime Zone, and Quick Scene have been bringing the best possible scene diagrams to court. These diagramming applications have all the tools an investigator needs to create detailed, 2D and 3D diagrams. Since they were designed specifically for drawing crash and crime scenes, there are not a lot of unnecessary features to get in the way. Whether you take measurements at a scene with a tape measure, a total station, or a 3D laser scanner, it’s easy to bring your data into the diagramming software and show the location of evidence and other points, all according to your exact measurements.

(1) The Harold Review, Decatur, IL, Police Fatal Accident Investigation Team Specializes in Crash Clues, 2/17/2013
(2) WWW.LAWOFFICER.COM, A New Piece of Evidence, 12/2012

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