The following is content sponsored by Leica Geosystems
Laser scanning technology has radically advanced the documentation capabilities of crime scene investigators. While the scanner has made a quantum leap in accuracy and comprehensiveness, the integrity of the scene and the scan data ultimately depends upon investigators carefully following well-established protocols and procedures as well as forging new guidelines as technology advances.
By avoiding the following laser scanning mistakes, crime scene investigators can be confident they’re on track to deliver accurate and admissible data in this critical first stage of the criminal justice path.
No. 1: Failing to Create a Scan Plan
The early stages of a crime scene investigation can be hectic. Questions need to be answered as quickly as possible. Upon arrival, for example, a crime scene investigator might face queries such as: What’s the victim’s identity? Is there a weapon present? What is the serial number of the gun? How many shots were fired? The answers may be revealed by searching the scene, but first the scene must be thoroughly documented. However, before proceeding with laser scanning, a few minutes should be set aside to create a “scan plan.” A scan plan is a quick sketch of the scene layout that is prepared after the initial scene walkthrough but before documentation starts. Laying out a quick plan on paper helps determine the best setup locations for the scanner and targets so that the scene can be thoroughly documented in as few steps as possible. The plan also creates a written record of your activities at the scene.
No. 2: Showing Up with Uncharged Batteries
Preparedness is key. Showing up at a scene with dead or partially charged batteries will lead to embarrassing scene-processing delays. Although some scanners can operate on power plugs, there is no excuse for not being prepared and ready to go with fully charged batteries. Lithium-ion batteries can remain on the charger without harm during scanner downtime. So immediately upon returning from an assignment, place any dead batteries back onto the charger. Also, rotate batteries regularly so you can be sure that, when the call comes, you will be ready to get straight to work.
No.3: Altering the Scene Before Scanning
Many crime scene investigators prefer to complete overall scene photographs prior to scanning, and this may be a good approach. But it is important that scanning be completed as soon as practical after those initial photos are taken. Waiting too long can lead to discrepancies between the two sets of documentation, and that can raise questions and compromise the investigation.
No. 4: Not Utilizing NIST Traceable Interim Validation Tools
The National Forensic Science Technology Center now recommends that crime scene measurements have National Institute of Standards and Technology (NIST) traceability. According the center’s 2013 guidelines, measurements should be accurate to within 0.25 inch and “the accuracy of all measuring devices should be ensured by comparison to a measure of certified accuracy, such as a NIST traceable ruler.” Additionally, a criterion for federal court admissibility of scientific evidence under the Daubert Standard requires the establishment and maintenance of operational guidelines and protocols for conducting analytical testing, monitoring quality assurance and controls, periodic calibration checks and validations. When evaluating scanner performance specifications, look for technology and manufacturers that provides verifiable accuracy. Otherwise, your scan data evidence and exhibits may not hold up in court.
No. 5: Not Repeating Scans After New Evidence is Discovered
Once the scene is photographed and scanned, the next step is scene processing. During the processing, items are moved and new evidence may be revealed. Don’t forget to re-scan the areas where new evidence is discovered. For example, consider that a decedent is removed from the scene and a weapon is discovered under the body. If the area is re-scanned, before-and-after views can be layered into the point cloud and toggled on and off from view using 3D point cloud processing software.
No. 6: Not Making Redundant Copies of Data
Before departing the crime scene, always copy your data onto an authorized flash drive. Redundant copies of data are good policy and protect the investigation against accidental loss. However, remember that scan data from a crime scene is evidence, and each copy must be properly secured and tracked.
Whether the measurement tool is a traditional tape or a high-tech laser scanner, maintaining scene integrity and delivering incontrovertible data depends on circumspection and adherence to procedures and protocols. Avoid these six critical laser scanning mistakes, and you can be confident that your work will stay on track.
If you'd like additional information on how to safeguard your crime scene laser scan data, please contact us.