Defending Your Scene Diagrams in Court

As an investigator, you may often be called upon to present your findings in the courtroom in front of a skeptical jury and an attorney who would just love to prove you wrong.  Your diagrams of the scene are an important part of your investigation and you want to make sure you can prove they are completely accurate. So, what are some rules to follow for ensuring that your methodology for preparing a diagram and diagramming the scene itself will be credible enough to withstand courtroom scrutiny?

Document and Measure Carefully, Photograph Everything

“The first thing I can tell every investigator to do is document, document, and document some more,” says John Howell, CEO of John Howell & Associates, an accident reconstruction firm based in Las Vegas, Nevada. Howell, a former reconstructionist for Washoe County Sheriff’s Office in Reno, and for the Nevada Highway Patrol, always starts his documentation by making a field sketch—what he calls the “first level” of documentation. The sketch should be complete, clear and easily understandable, and as accurate as you can make it. The field sketch, he notes, is basically notes, measurements, and information. “Very seldom will it be seen,” Howell explains, “but if you don’t have a firm base from which to start preparing a diagram, you’re going to wind up with problems, and with a diagram that is not a proper view or reconstruction of the scene. If this happens just once, your reputation suffers greatly.”

Next, Howell continues, it is vital to photograph everything at the scene, especially if you’re fortunate enough to be able to visit the scene while it’s still intact. “The photos give a little more of a clue as to where everything is, and gives you a feeling when you’re actually preparing the diagram of what occurred,” said Howell.  If you cannot actually photograph the scene, which is common since reconstructionists may be assigned a case months or years after the incident happened, collect every photograph you can from all available sources.

Photograph of overturned car with 3D diagram.

Photograph of overturned car with 3D diagram.

Mike Bann, of Accident Measurement Mapping in Yuma, Arizona, agrees with Howell on the pivotal importance of taking or obtaining photos of a scene. “The photos should reflect what’s on the drawing,” says Bann. “If the corner of the fender, the lightpole, and the corner of the house line up, these items must also line up in the drawing.”

Choose An Accurate, Tailored Drawing Program

Another consideration important to building a solid diagram is its overall look, according to Bann. “There are always a ton of pictures,” he said. “What you really need to be sure of is that you give the diagram the most realistic look because what you’re trying to reconstruct is the actual scene.”  To achieve such a realistic diagram, Bann recommends using an accurate, reliable and feature-rich software drawing program.  Both Bann and Howell use The Crash Zone from The CAD Zone of Beaverton, Oregon.

While there are many other drawing programs available, they prefer The Crash Zone because it is specifically tailored to be used by crash and crime scene investigators. It contains many features that are just for drawing 2D and 3D crash scenes, such as thousands of predrawn symbols, a vehicle specifications database, and special linetypes that let you turn any line, arc, or curve into a guardrail, skidmark, scuff mark, or fence. Crash Zone also includes a Road Builder toolbox, a 3D Body Poser toolbox, and a unique Easy Intersection toolbox for creating intersections with turn lanes, bus turnouts, crosswalks, and more.

Howell, who also teaches reconstruction classes, favors The Crash Zone because of its short learning curve. Many trainers comment that they can get a student up and running in the Crash Zone and producing detailed, accurate diagrams in under 10 hours of classroom time. Other diagramming programs on the market which are not designed for accident reconstruction can require 200-plus hours just to master the basics, Howell noted.

Showing Points of View May Be Critical

Bann likes The Crash Zone because it allows him to recreate an accident scene as vividly as possible with symbols like curbs, guardrails, fences, vehicles, trees and shrubs. After all, Bann said, “If you’re having trouble with your scenes in court, it may be because there’s not enough information in them and you’ve made them too simple.” Adding more details to the diagram that relate exactly to the photographs will make it easier for people to relate your diagrams to the actual scene.

Just how crucial it is to be thorough with diagramming is evident when witnesses give their testimony and it doesn’t quite match with where they were standing at the scene at the time the accident occurred. For example, Bann recalls one case that his firm handled for the City of Yuma involving an intersection, gas station and a convenience store. The area covered a quarter-mile by quarter-mile distance. “It (the diagram)  had to show  the windows and elevations of objects because people were standing from 50 feet to 1,000 feet away, claiming they saw certain things,” Bann explains. “In reality, when we used Crash Zone to produce the diagram showing shrubbery, gas pumps, and all the poles, they could not have seen much with these obstructions,” Bann added.

As part of his diagrams, Bann uses The Crash Zone’s 3-D feature to provide optimal views of all angles, objects, people and locations. “When you build the scene to scale and put it in 3-D, it really shows the possible Point of View of witnesses and it becomes obvious if what was stated to have occurred really did or could have,” Bann said. “The 3-D capability eliminates an attack by the opposition in court.”

Anticipate Questions of Scale

Bobby Jones, a police officer and accident reconstructionist in Knoxville, Tennessee for more than 20 years, has some tips on using scale to your advantage in an electronic diagram program.  While Jones measures and then draws the entire scene with complete accuracy in The Crash Zone, he often only prints a portion of the drawing in order to show the important points on one page. He also prints the diagrams at an odd scale so the other side will have to do their own measuring.

In one of Jones’ courtroom battles the opposing team tried to challenge the scale of his diagram by overlaying their printed version on an aerial photograph and showing that it didn’t match. The problem with their approach was that Jones’ original diagram was printed at a scale of  1” = 17.654’ and the opposition had used a copier to make a transparency of the diagram, reducing and enlarging it to approximate the photograph’s scale. Jones informed the jury that the scale of their transparency had been manipulated by a copier, then he overlayed a transparency he created from his original Crash Zone diagram, which of course had the correct scale.  Jones says “The attorney I was working for took full advantage of the slip by the defense and absolutely just spanked the opposing expert.”

Generous Labeling Strengthens Diagram

If there’s one aspect of an investigation with which the prosecution will get hung up, it’s arguing over inches, Howell said. His advice? “Understand the limits of the medium. You’re not going to be able to diagram down to a quarter of an inch. Don’t split hairs over it.” In other words, be realistic when arguing about the accuracy of your diagram. Even though points entered into The Crash Zone have coordinates that are accurate to more than + or -.00000001”, it is obviously not practical to measure the physical points at the scene to that kind of accuracy.

The only other target for wrangling within a diagram, Howell added, seems to be the location of where the diagram was created. “They (the  opposing attorneys) try to harp on accuracy,” he said. “Be sure you label everything, keep it clear and concise, and make sure it matches the photographs.” This is particularly important to a jury. Why? “Because the first time that one of the jurors looks at the diagram and sees a discrepancy, you won’t get their mind off it,” Howell cautions. “You’ll lose everything you said to this juror. Then you’ve lost all of your credibility. And credibility is everything in this business.”

Contributed by Bob Galvin, a Portland, Oregon freelance writer who writes on topics covering technology used by law enforcement to investigate crime and crash scenes.

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