Tape measures, measuring wheels, rulers, pencils, note pads and graph paper: as crime scene investigators, we have all spent hours at scenes taking measurements and creating rough sketches with these tools. Once the measurements and rough sketches are complete, it’s back to the office, where we might spend hours, or even days, creating a finished diagram for our reports. These diagrams may be hand drawn or created with a computer aided drafting (CAD) program. For many CSIs, diagramming can be the bane of their existence since it can be very labor intensive, taking up significant manpower hours—hours needed for other post-scene duties such as processing, evidence packaging and submission, analysis and report writing. Drawing is simply not a favorite part of the job. 

Owen McDonnell
Retired Lieutenant/Supervisor, Caddo Sheriff’s Office Crime Scene Investigations Division

Fortunately, technology can help. For example, surveying equipment, such as a Total Station and two-dimensional scene capture, can be used for crime scene documentation. These methods offer some advantages over traditional tools. For large scenes, time savings can be realized during on-scene data capture. In addition, multiple locations can be tied together through back sighting. Equipment operators select points to be recorded in the scene and reposition as needed. The biggest advantage comes from the ability to capture the relationship of items in the scene. This data can then be imported into CAD software and correlated. 

But these techniques have drawbacks. First, they still require at least two people to capture data, and using them can be just as time-consuming as the conventional tape and measure method. While these systems work well for outdoor scenes, their practicality for use on indoor scenes is extremely limited. Finally, although CAD programs have many benefits, using them to create final two-dimensional diagrams is still fairly labor intensive and requires moderate computer skills.  

More importantly, both manual and two-dimensional scanners suffer from the same fatal flaw: they are dependent on the operators’ subjective judgments made on the scene. Operators on-scene decide what to measure based on what they feel is important to the case. As CSIs, we make informed judgements, but those judgements are based on the information we have while processing the scene. I have both worked and reviewed cases where items are photographed but not measured because they seemed insignificant at the on-scene investigation. It is only later that we realize these items are significant and that measurements could have added context. By then, it’s too late. CSIs only get one shot at a crime scene, and we make the best decisions we can based on the information we have. Unfortunately, we cannot always predict what might be needed later in the investigation. 

Three-dimensional scene scanners are the latest incarnation of scene documentation, and they address many of these concerns. These tools combine 360° camera capture with laser capture of millions of measurements. Quite simply, if the instrument can “see” it, it measures it. The photographs taken can then be viewed alone, or the software can stitch together all images to create a 360° image allowing the viewer to see the scene from the perspective of the camera. The high-resolution images also allow the viewer to zoom and pan from one location to another. In addition, multiple locations can be tied to each other to allow the creation of a virtual walk-through of the locations. Measurements can be displayed by selecting points in the image. 

3-D scanners allow the CSI, detective, supervisor, analyst and reconstructionist to revisit the scene from a computer. For court purposes, it allows attorneys and jurors to visit the crime scene from the courtroom. For years, we have attempted to allow the court to “see” crime scenes using photographs, video, and diagrams. This new technology brings us one step closer to achieving this goal. It also provides transparency by allowing defense experts to “visit” the crime scene months or years later. Depending on the software package, the data acquired can be used by crime scene analysts/reconstructionist to show their findings using forensic animations. 

3-D scanning equipment is certainly the latest, greatest thing. But at $50 to $150 K, depending on the system and software options chosen, the cost can be prohibitive for many agencies. Keep in mind that the purchase price is not the final cost to the agency; you must also factor in training costs, the need for additional data storage on your servers, and software updates. In order to develop realistic cost per scene estimates and determine a return on investment, each agency must consider how many times per year they would use this technology. Over time, the price may drop as these systems become more common, but for now, budgetary constraints are the greatest obstacle to implementing this technology. Grants can provide a source of funding, but as all managers know, competition is fierce. 

In considering these systems, remember that they are not limited to crime scene work; they may also be used for accident reconstruction and investigations. You may be able to propose the purchase by working with your traffic crash investigations unit to meet the needs of both divisions. An alternate solution may be to establish cooperative ventures with agencies in your area to purchase a system. While there are pitfalls with any such agreement, if you already have working relationships between agencies in your area, this may be a viable option.

Today, there are many choices available to accomplish the task of documenting and creating a demonstrative presentation of the scene. The method used is dictated by the scene, the available resources and equipment, and budgetary considerations. As crime scene investigators, we always want to provide the best possible documentation. Be creative in your approach and do the best work you can with the tools you have. 

Owen McDonnell retired as the Lieutenant/Supervisor of the Caddo Sheriff’s Office Crime Scene Investigations Division in Shreveport, LA after 31 years. He is the owner of M.O. Forensics LLC and provides consulting and training in crime scene and fingerprint development and comparison techniques, as well as heading workshops through IAI. He holds IAI certifications as a Senior Crime Scene Analyst, Ten Print Fingerprint Examiner and Latent Print Examiner. McDonnell holds a Master of Forensic Science Administration Degree from Oklahoma State University Center for Health Sciences.