thanks to low
3-D CAD software.
The man claimed he was acting in self-defense. When an intruder suddenly entered his motel room, the victim said he had no choice but to strike the man with a lamp, knocking him unconscious.
But the evidence told a different story. Using drawings created by a three-dimensional computer-aided drafting (CAD) program, the police were able to show that the intruder was actually well inside the room and sitting in a chair when he was struck, not at the door as the alleged victim claimed.
By carefully measuring the angle at which blood spots hit the motel wall and floor, the police were able to reconstruct exactly where the accused was situated when he was hit. What had looked like an act of self-defense against an attack now appeared to be an ambush.
According to Paul Breuninger, a police investigator and 25-year veteran with the Cook County Police Department, witness testimony is always the weakest link in any investigation. Hence the need to corroborate or refute witness statements using physical evidence. "With CAD you can create an actual model of the crime scene and view it from any angle," he said. "It allows you to view just what the witness says he saw."
For years, police have done crime reconstruction using tape measurements and, in the case of blood spatter analysis, pieces of string. Then the information had to be carefully drawn to scale -- a task that was extremely time-consuming.
Since 1985, Breuninger has been using CAD software to do the work for him. Unable to afford costly CAD software at first, Breuninger wrote his own program. Later, he bought one of the early 3-D CAD programs. Today, 3-D CAD software can be purchased for hundreds of dollars instead of the thousands it cost a few years ago.
Breuninger works with a product called DataCAD, a $300 architectural program produced by CadKey Inc. Easy to use, DataCAD needs just two points from which it can render a wall versus the 16 lines required by other 3-D CAD programs. Doors, windows and other architectural elements can be easily added and all drawn to exact scale, according to Breuninger.
From science to law enforcement, 3-D drawings are valued for their ability to portray information in an understandable way. Whether it's viewing a 3-D model of a DNA molecule or a crime scene, the mind absorbs information displayed in three dimensions like a sponge. By working in three dimensions, CAD users can create scenes that can be viewed from any angle. Suddenly, very technical evidence can be visualized by nontechnical people. Juries can "view" crime scenes and see the location of evidence. They can view what a witness claims to have seen or not seen. And as Breuninger pointed out, "evidence doesn't lie."
Breuninger recalled a case in which a man told authorities he had not seen a murder that occurred in his kitchen. He claimed he was in the attached garage at the time, and the kitchen was not in his line of sight. By re-creating an accurate model of the man's house, Breuninger depicted the view from the garage toward the kitchen, verifying it was actually possible to observe something happening inside the kitchen. From the reconstruction, authorities were able to determine that the man could have seen the murder.
A PRECISION TOOL
So why use CAD and not one of those popular graphics drawing programs to reconstruct crime scenes? According to Breuninger, the reason is precision. "You tell CAD the exact dimension and you get a scaled drawing," he said. For people who use CorelDraw and other drawing software, accuracy is not an issue. As a result, mainstream drawing packages have limited controls for rendering measured drawings, while 3-D CAD programs are highly accurate, very math-dependent and require a math co-processor in the computer to work effectively.
Fortunately, setting up a 3-D crime reconstruction program isn't going to bust the typical police department's budget. Except for the co-processor, hardware requirements for operating 3-D CAD programs are minimal, according to Breuninger. He said that a 386 PC, with eight megabytes of RAM, running MS-DOS, can handle the drawings used in crime reconstruction. Since most police departments probably carry that kind of equipment, the only other computer-related investment would be software.
What's also needed, however, is the kind of training that will teach an officer or detective how to create 3-D drawings for use in courts. Unfortunately, most training programs are geared toward high-end applications for drafting and architectural design, taking months to complete. That's not going to help police officers and detectives, given their busy schedules. To help law enforcement agencies master the mysteries of 3-D crime, Breuninger teaches a five-day, 40-hour course designed specifically for police investigators, traffic accident reconstructionists and evidence technicians. The course, "Introduction to Crime Scene Reconstruction Using 3-D Computer-Aided Drafting," has students creating 3-D models in less than a week, according to Breuninger, who believes the class to be the only one of its kind in the country.
Breuninger's first reconstructions were produced by programming a computer to instruct a pen plotter what to draw. These drawings, while accurate, weren't three-dimensional. Today, his 3-D model drawings can reconstruct how a series of events unfolded. Reconstructions include not just the layout of crime scenes, but also the flight path of projectiles that have ended up in walls, floors, ceilings, vehicles or victims.
In 1993, Breuninger was asked to reconstruct a crime scene of a mass murder that took place at a restaurant in Palatine, Ill. Without any witnesses, the police had to work with just pieces of evidence to create a picture of what happened. One of the methods Breuninger used to investigate that crime and others was reconstructing the flight path of the bullets. By measuring the angle at which bullets struck the wall, and then reconstructing their trajectory on a 3-D image, Breuninger was able to determine the height of the gunman.
When Breuninger heads to a crime scene, he takes with him a Hewlett-Packard 200LX palmtop computer for both capturing data and creating the first 3-D models of the scene. He uses both tape measures and laser measuring devices to calculate everything from the length of a room to the distance from a door to a window or the span between two pieces of furniture. The DataCAD software, which Breuninger was able to configure for operation on the palmtop, creates a 3-D shape based on distances taken in three directions from a reference point referred to as "absolute zero." The computer then creates a wire frame model of the shape based on the measurements. Breuninger stores all the data in the palmtop using a six megabyte flash disk card. Once the data is transferred to a desktop system, the model can be completed either as a wire frame or as a solid image which can be viewed at any perspective.
With pictures supposedly worth a thousand words, police are beginning to create animation from 3-D reconstructions in the hopes that moving models of crime scenes will add even more support to the evidence they collect. Breuninger assisted the Illinois state police to create an animation taken from 3-D CAD drawings from the crime scene of a homicide. He also has taken 3-D models and converted them into Virtual Reality Model Language (VRML), making them available on the World Wide Web. According to Breuninger, anyone with a VRML-enabled browser (such as 3D Live from Netscape) can virtually walk through a 3-D crime scene that's been placed on a Web page.
Audio capabilities also can be added to the VRML model, allowing viewers to hear descriptions of the evidence. Such adaptations will make it possible for experts and investigators in another city or state -- familiar with crimes of a similar nature -- to assist with an investigation.
With the use of 3-D models for crime reconstruction becoming more widespread in courts, it seems certain that the adoption of 3-D CAD by police departments will grow. While the lack of training courses geared toward law enforcement might hamper the growth of CAD at first, the introduction of more user-friendly CAD software should speed up adoption. But with or without limitations, 3-D CAD happens to be a great investigative tool, said Breuninger, "because it creates a picture from a camera that wasn't at the crime scene."
For a sample of 3-D models, go to: , or . A 3-D browser plug-in, such as "Live3-D " can be obtained at .