Each crime scene is unique—and fragile. From the minute the scene emerges, it ages, rapidly making accurate collection of evidence pivotal for understanding the likely chain of events. The development of digital evidence technology has become an invaluable tool for agencies that use it to preserve scene evidence. Of equal importance is the ability to create a detailed 3-D, electronic diagram of a crime scene for every crime case presented to a jury.
The diagram is just one of several crime scene documentation methods. Photography, video, total stations, laser measurement and scanning systems, and photogrammetry are tools employed to help capture scene evidence from different perspectives. None of these methods is self-sufficient in a court case. Officer and witness testimony support this evidence.
In fact, the crime scene diagram is itself a piece of evidence, argues Jon Priest, president-elect of the Association for Crime Scene Reconstruction. “It becomes discoverable because it is something that the defense (in a court case) can use to support or refute what it is they’re arguing,” says Priest. “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,” he says. And Priest would know: He’s spent the last 28 years of his 32-year career with the Denver (Colo.) Police Department investigating violent crimes, as well as 20 years as a crime scene reconstructionist.
Clear Bullet Trajectory
Crimes happen in- and outdoors. For Brad Joice, owner of Forensic Mapping Services, the ability to map crime scenes in 3-D—especially indoors—has become integral to court presentations.
“The evidentiary and probative value of that three-dimensional diagram is much stronger for an indoor scene than an outdoor scene,” explains Joice, who also is an investigator in the Forensic Identification Unit of the York Regional Police in Newmarket, Ontario, Canada. “For instance, we can measure a shooting scene with the 3-D aspect in mind and create trajectory analysis,” he says. “We can show that in court.”
Joice uses MapScenes Evidence Recorder (EVR) and MapScenes Forensic CAD (computer-aided drafting) software for creating diagrams of his shooting scenes to show the 3-D trajectory of a bullet. Most of his other crime scenes are mapped and measured in 2-D because far more points must be measured for a 3-D drawing. But with an interior crime scene there’s the opportunity to measure with great accuracy the dimensions of room, lending a true representation of interior dimensions in which the crime has occurred.
How It Works
Joice recalls investigating an indoor crime scene where the victim was shot in a bedroom of his house. There were two males in the bedroom, and at some point a gun was fired. The victim had a fatal gunshot wound to the chest. The bullet traveled through him, exited through his side and then passed through the wall in the first bedroom and into the adjacent bedroom. The bullet kept traveling until it penetrated the wall on the opposite side of this second bedroom.
Joice measured both bedrooms in 3-D. He then drew the trajectory from the first bedroom through the wall into the other bedroom and could place where the victim was at the time the weapon was fired.
“It was a valuable tool in court because although we weren’t able to give the victim’s exact position, I could give a range of positions, such as showing how the victim had to be between two specific points at the moment the shooting occurred,” says Joice. “The diagram narrowed down his position to about a four-foot area along the trajectory path of where the victim had to be when the gun went off.”
Joice also uses the MapScenes Capture software, allowing him to add animation to scenes, including animated cameras and walkthroughs. “I can place cameras in any position including witness/subject positions to get realistic views from their positions,” he says
All Key Data Collected
The Canyon County (Idaho) Sheriff’s Office investigated at least 40 scenes involving homicides, suicides and unattended deaths in 2011. To process these scenes, the agency uses a total station and a TDS Recon Pocket Computer, along with The CAD Zone Inc.’s Pocket Zone data collection software. Measurements that are collected are then brought into The Crime Zone CAD software to create either a 2-D or 3-D diagram.
This technology has made the job of scene investigation easier for Steven Petersen, Criminalist for the Canyon County Sheriff’s Office Forensic Services. Petersen says that the Pocket Zone software is a CAD program and data collector in one. He can draw a diagram with it while running the total station and having his assistant on the total station’s prism pole.
“I can add any details as needed while I’m gathering the digital data,” says Petersen. What’s more, he says, when he uses the total station to record all of the measurement and evidence points at the scene, the data is ready to bring into his diagramming software with no conversion. “The Pocket Zone file is an actual CAD drawing that can be opened directly in The Crime Zone.”
The software also increases efficiency at the scene by allowing operators to label given points with the total station, place symbols, and draw lines, arcs and curves with the Pocket Zone data collector.
The ability to then 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.”
Features Galore
Most drawing programs today offer a comprehensive symbols library, which match closely with what an investigator sees in his crime scene. Accurate distance measurements are also a breeze.
“If a suspect is at a certain distance from an officer, then this can explain and justify the officer’s use of force, for example,” says Peterson. “To be able to show those distances quickly and easily is key.”
Layering is a popular feature of today’s diagram software. For example, walls, doors and windows can be one layer of the diagram. The next layer may include furniture. Still another layer may show bullet trajectory. The benefit: You can activate specific layers to emphasize precisely the information you desire.
Another advantage of digital crime scene diagrams: They can be saved in a .PDF format or other format that can be shared with others who are interested in the case. As a result, says Darling, the digital diagram can be put on a network, “and immediately any of our investigators working on the case can look at that diagram. And, I can burn it to a CD and send to the prosecutor, who can then make copies for the defense.”
The Ability to Animate
Scene animation is another feature included in many drawing programs.
Animations can be highly instructive for showing the possible chain of events at a crime scene, but they also can be misunderstood or viewed as too subjective—or worse, as a distortion of a scene’s criminal activity.
Mike Darling, Crime Scene Technician with Redding (Calif.) PD’s Crime Scene Unit, asserts that the effective use of animation depends on what a testifying investigator is trying to illustrate. Animation is a 3-D diagram in motion, created from the physical evidence and measurements collected from a scene.
In a vehicle collision, for example, it’s fairly easy to understand from what directions the cars arrived at impact, so animating an electronic diagram of this scene could be perfectly valid.
“You know from the debris at the scene exactly where the vehicles met,” says Darling. “And you know from the skids exactly where they left, and from looking at the skids you can tell how they rotated. If you depict these vehicles following those movements and skids, there isn’t a subjective aspect to it.”
Darling cites another scene he investigated. “We had blood spatter evidence,” he says. “There were multiple strikes at different locations in the building. I could reconstruct the activity strictly from the blood spatter evidence. It’s not a guess. I could isolate the exact location where these strikes happened down to within a spherical area of just a few inches because of the blood spatter evidence.”
Better Integrity, More Views
Crime scenes will always be fragile. Digital diagramming can offer a way to preserve a model of what happened in a format that’s easily presented, manipulated and created. With accurate measurements and careful presentation, digital diagrams can be an invaluable asset in the documentation and prosecution of crime.