Mapping Scenes
Written by Bob Galvin   

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Crime-scene documentation hinges on forensic expertise and versatile technology

WHEN A CRIME has been committed, the crime scene is ground zero for the ensuing investigation. A core part of the investigation is


scene documentation because this activity will create a permanent written and visual record of the scene, the conditions at the scene, and the evidence within it. For this reason, accurately measuring and mapping the scene will prove valuable in showing, with a scaled diagram, what evidence exists and the relationship of these items of evidence to one another. It is a delicate process requiring strong investigative expertise and knowledge of evidence documentation. And today’s technology is a key link in this process.

This article will explain the critical nature of scene documentation, the suggested technology available for mapping the scene, and the benefits this technology yields to crime-scene investigators as they present crime-scene evidence in court.

Forensic mapping combines sciences

Once a crime scene is present, the process of documenting it is called forensic mapping, a term used by investigators called upon to collect evidence at crash and crime scenes.

What is forensic mapping? “I think police officers and reconstructionists define forensic mapping as a combination of two sciences,” said

Best Practices for
Total Station Setup

If you are using a total station to map your crime scene—whether it is a homicide or car crash—proper setup of this instrument is crucial to ensuring accurate measurements, collection of all relevant evidence, and preservation of the evidence.

Remember, too, that the total station is part of a scene-documentation process. In this process, you will map your scene using the total station’s onboard software, or using an external data collector. Since most mapping teams use external data collectors and software, we will focus on this method of mapping.

Here are some tips on how to make this process smooth and successful:

  • When you arrive at the scene, walk around to determine how much of the surrounding area you will want to include in your diagram. Then, decide where to locate your reference point—the place where the total station will be located. Then, choose a reference measurement point—a fixed point located at a known distance, usually 25, 50 or 100 feet from the reference point. This distance is measured by hand with a measuring tape and, if possible, the reference point and the reference measurement point should be somewhat permanent, just in case you need to revisit the scene at a later date to gather more evidence.
  • Set up and level the total station tripod over your established reference point. The instrument should be at eye level when you are standing.
  • Attach and set up the data collector.
  • Turn on the total station and configure it.
  • Using your data-collection software, establish your location in the map and record a measurement between the reference and reference measurement points.
  • Important: Compare the distance reported by your software to the distance you measured by hand. If the distance set out between the points was 50 feet, then your total station and data-collection software should also report 50 feet. This process ensures that your total station is measuring distances correctly. Defense attorneys typically will question accuracy of measurements and procedures used at the scene, and ask you to prove that your measurements are accurate.
  • As you map the scene, use a code library to record consistent descriptions of the points being measured. If your data collector supports it, create line work at the scene as you measure, saving you from needing to “connect the dots” back at the office.
  • Periodically—throughout the course of mapping and at the end of your scene collection—you should turn back and record a “check shot” to the reference measurement point. Doing so validates that your total station hasn’t been accidentally disturbed and that all angles and distances were measured correctly.
  • Once the data has been imported into your drawing program, you can begin analyzing the evidence points. From these points you can create diagrams, 3D views, animation, and reports.

Chuck Veppert, a retired reconstructionist with the Ohio State Patrol and a member of the Professional Society of Forensic Mapping. “These two sciences are forensic-scene investigation and the drawing of specific locations at crime scenes. A forensic investigator has the training and knowledge to understand and identify crime- or crash-scene evidence, how best to document it, and the ability to present his or her findings in court.”

Total station takes the lead role

The total station is probably the most ubiquitous tool working at crash and crime scenes. This is due to this technology’s portability, accuracy, fast operation, and low cost compared to other mapping technologies. A total station is a multi-purpose electronic instrument used for years by surveyors, but also by law-enforcement agencies most seriously since the 1990s. Using a built-in electronic distance meter (EDM), a total station measures horizontal distances, slope distances, angles, vertical height differences, and three-dimensional coordinates. Measurements are mapped with an onboard or portable data collector that is usually linked to data-recording software. Back at the law-enforcement agency’s office, the recorded evidence is downloaded into a diagramming software program that produces a detailed and scaled diagram, in 2D or 3D, showing key attributes of a crash or crime scene.

These components (total station, data collector and evidence-recording software, and CAD program) allow the process of scene documentation to occur seamlessly. The technology, of course, does not operate at crime scenes via remote control. Instead, the technology is a tool with value that can only be realized by an experienced scene investigator or scene-reconstruction professional. But even the most experienced investigator using the most current mapping technology can face challenges with evidence collection.

Focus on the ‘secondary’ crime-scene area

In the view of Hayden Baldwin, the executive director for the International Crime Scene Investigators Association (ICSIA), securing a crime scene is the biggest challenge for nearly every law-enforcement agency. It may sound like a simple process, he said, but not always. “If you’re looking at a crime scene in a building, it is fairly easy to secure the structure and access the building,” Baldwin explained. “But an outdoor crime scene on a busy highway or Interstate becomes more complicated. This can require more manpower and higher technology.”

Baldwin stated that all crime scenes have a primary and a secondary area. “It is the secondary area that can be extremely critical to the scene and that needs to be safeguarded,” he said. “We all understand bodies lying in a room. So, the primary scene would be that room. The secondary area is all avenues that lead to that room and that lead to the structure.”

Need to prioritize evidence

Sgt. Dave Forystek, an officer with the Flint (Michigan) Police Department’s Traffic Division, knows well some of the challenges of investigating crime scenes. “One of the biggest challenges is identifying what evidence actually is part of the crime scene and what isn’t before we even begin our mapping of the crime scene,” Forystek said. “If we go to a crime scene where maybe there was a shooting or an assault of some kind and there is all this evidence, it is hard to tell what is fresh and what isn’t.”

This is where years of scene investigation experience pays off. For example, Forystek suggests that there are scene nuances to carefully consider, such as the location and condition of a piece of evidence. Is it lying on the cement? Is it clean underneath or dirty? Has liquid pooled on one side? Has rain water seeped into it? Or, if the evidence is lying in the grass, has the grass turned brown underneath?

Whatever the evidence is or its condition, “making sure it is going to be unchanged as much as possible until you can get it mapped, collected and photographed” is key, Forystek said. He gets plenty of practice investigating crime scenes because crime in Flint is high. For example, in 2010 there were 66 homicides within 12 months. A typical scene will be filled with any variety of evidence including cartridge cases from shootings, blood spatter, bodies, and holes in a wall or in a car door.

Real-time evidence mapping, 3D views are big benefits

The sergeant maps his scenes using a Sokkia SRX5 fully-robotic, single operator total station with an Archer Field PC that runs MapScenes Evi-dence Recorder (EVR) Version 7.0 and MapScenes Forensic CAD software. The total station cuts manpower in half, and can shoot a scene of up to 1,500 feet requiring only one operator. The scene evidence is mapped and recorded by MapScenes EVR. With the press of a button, the software captures angles and distances from the total station and stores the 3D position. Finally, the points are downloaded into the Forensic CAD software, usually in 3D, to clearly show scene evidence, and vertical mapping details such as blood spatter and bullet trajectories, among other details.

Forystek notes that the evidence recording software’s ability to show scene points and line work as he shoots is a huge advantage because it means there are no missed points. Further-more, the software’s 3D-view feature yields essential visual verification of point elevations.

The Forensic CAD program is equally compelling. “If the evidence has been collected properly, you can really do some great things (with the CAD software) to show different surfaces and how bullets traveled through them, or how they may have affected a crash scene,” said Forystek.

Clearly, using the best available technology to measure and map a crime scene is pivotal, as Forystek has learned. There are several total-station brands to choose from. Veppert of the Professional Society of Forensic Mapping has mapped many crash scenes in his career and uses a total station. He also is an advisor to the Summit Metro Crash Response Team (SMcRT) in Summit County, Ohio, which, after considering several brands of total stations, chose Sokkia.

“Sokkia, I know for a fact, has really gone out of its way to make sure we have the options and applications that are most needed by police in forensic mapping,” Veppert said.

Tools to document a major homicide and a bus crash

Like Forystek, Mark Wood, a Sherman (Texas) Police Department patrol officer, realizes how the right technology can aid in the documentation of a crime scene. After using the Autodesk AutoSketch diagramming software for his crime scenes, he had to find another program, since this one was oriented primarily to engineers. Like Forystek, Wood uses a Sokkia total station—in this case, a Sokkia SET 30R3 along with Archer Data Col-lector with Evidence Recorder, and Mapscenes EVR/Forensic CAD because, as he puts it, these software programs are “reconstruction based.”

The SET5 30R3 total station uses high-precision reflectorless distance measuring with a narrow-beam visible laser, making it well suited to perform in tough environments.

Two incidents that Wood investigated offer insights on how technology dramatically ensures proper crime-scene mapping. In one incident, a man broke into the apartment of his estranged wife and killed her, his son, and an 18-month-old child with a knife, dismembering the bodies and taking the parts with him. Wood used his total station to map the scene since it could easily be taken from room to room by moving to previously established reference points. Most total stations used today have internal compensators that can increase the accuracy of the horizontal and vertical angles measured at the scene. With proper training and software, users can move their instrument throughout a building and achieve great results.

“The aspect I like about the total station is that anything you see—and cannot see—can be mapped,” said Wood.

Try vertical mapping

At many crime scenes, “vertical mapping” is particularly valuable. It involves mapping a wall, building, or a side view of a vehicle, for example. Vertical mapping is performed for dimensions that need to be mapped from a vertical surface, and often include blood spatter, bullet trajectories, and marks or angles in buildings, cars, bodies, or among other objects.

In another incident that Wood investigated, a bus traveling out of Houston went off the road in Sherman, crashing into a creek and killing 17 people. Again, Wood used the Sokkia SET 30R3 total station to map this scene. Reflectorless total stations will operate with or without a prism. As a prismless device, this total station can measure the distance to certain objects from virtually right up against its scope to several hundred or even several thousand feet away from the reference point location.

“We actually mapped the bus in 3D on all sides, noted Wood. “Then we mapped the scene in 3D because the bus fell into the creek. I took the 3D data points from the bus and imploded it into a 3D drawing in the Forensic CAD software so that I could show the whole scene in 3D.”

Technology Useful in Training

Technology used for scene investigations is particularly powerful in training classes. One trainer, Tony Kavan, an investigator with the Nebraska State Patrol’s Investigative Services Division, teaches students in his forensic-mapping classes how to set up a total station; map a location; move the total station and still be able to map; the basics of total-station operation; how to use software to download the data onto the computer; and how to use the CAD program so students can build a recognizable diagram and prepare it for exhibit to a jury.

“Juries expect technology from us,” said Kavan. The technology available through total stations and associated data collection/recording/diagramming software is what yields the clearest representation of crime scenes, events, and evidence. Kavan said his crime-scene investigation team uses a combination of photography, written reports, and scene diagrams to tie a crime scene together. What happens if a CAD drawing is missing a key measurement? No problem. Kavan can go back to his data-recording software and capture the needed measurement. “The better information you can give to a jury, the more informed of a decision they can make,” Kavan noted.

Use animation cautiously

This naturally begs the question of how valuable—and reliable—the use of animation can be in presenting reconstructed crime scenes in courtrooms. Baldwin of ICSIA feels it must be used wisely. “It can be a wild card in a courtroom,” Baldwin said. “There can be animation of a scene based on data that is not valid. This is why all crime scenes have to be based on facts that can be proved because when jurors see animation, they can tend to believe what they see.”

Forystek of Flint, Michigan, a police sergeant, noted that he started using the MapScenes Capture animation software, for example. He considers animation a great way to test theories about how crashes and crimes unfolded at their scenes.

“You’re visualizing the crash or crime event, but you’re letting the software help because it knows the physics, and the software can provide a 3D animation,” Forystek explained. “It is powerful to be able to show a shooter and how he moved, or how somebody was running and a bullet hit him and where he fell.”

Laser scanners are another option

Laser scanners are being used more widely for documenting crime scenes, as well. A 3D laser scanner allows the user to generate a panoramic photo of a crash or crime scene, then it measures several thousand highly accurate measurements per second of everything within its field of view. A drawing program is then used to create a diagram from selected points within the scanner’s database. One big advantage is that the scaled diagram gives a view of the scene that can be studied from any viewpoint.

“With laser scanners, you’ll get even higher accuracy (compared to total stations),” said Veppert. “But there is a very high difference in cost.” Scanners cost many thousands of dollars more than total stations, making them affordable mostly to larger police departments with big budgets, or to those that are able to acquire the technology through grant funding.

Meanwhile, Veppert feels total stations probably will continue to be a mainstay with law-enforcement agencies due to their affordability, ability to integrate easily with CAD software, their leap in accuracy within recent years, and the speed with which measurements can be taken. mmm

About the Author

This e-mail address is being protected from spam bots, you need JavaScript enabled to view it is a freelance writer who covers topics related to law enforcement and the technology of crime- and crash-scene reconstruction. His office is located in Oregon City, Oregon.

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