TECHNICAL NOTE ANTHROPOLOGY; GENERAL Debra A. Komar, 1 Ph.D.; Stephanie Davy-Jow, 1 Ph.D.; and Summer J. Decker, 2 Ph.D. The Use of a 3-D Laser Scanner to Document Ephemeral Evidence at Crime Scenes and Postmortem Examinations ABSTRACT: Proper documentation of physical evidence at both crimes scenes and postmortem examination is crucial for downstream analysis, interpretation, and presentation in court. Ephemeral or transient evidence poses particular challenges to investigators, as its very nature renders it diffi- cult or impossible to seize and maintain in its original physical state. The use of a hand-held three-dimensional (3-D) laser scanner is proposed to capture and document such evidence, both in the field and at autopsy. Advantages of the scanner over traditional means of documentation such as photography or casting include the ability to obtain measurements in all dimensions, the ability to reconstruct missing elements, and the ease with which generated images can be interpreted by the jury at trial. Potential scenarios warranting the use of the scanner are identified, and the limitations of its use are discussed. KEYWORDS: forensic science, physical evidence, documentation, crime scene, autopsy, forensic anthropology, forensic archeology, foren- sic photography, three-dimensional imaging Ephemeral or transient evidence is physical evidence that is temporary in nature and can be easily changed, altered, or lost over time (1). It cannot be seized and maintained in its original or in situ state. Documenting such evidence presents special chal- lenges to investigators. Traditional methods of documentation include photography, sketches and notes, electrostatic lifting, or casting (2) as well as field forms and video footage (3). An alterna- tive, supplemental method of documenting transient evidence may be the three-dimensional (3-D) laser scanner. The use of such scan- ners in forensic contexts has already been discussed in the use of bitemark analysis (4), cranial volume and area measurement (5), morphometric analysis of human facial shape variation (6), general craniometry (7), and documentation of injury at autopsy (8). Capable of generating high-resolution 3-D digital images, laser scanners are available in both hand-held and stationary units. In the past 10 years, advanced scanners have been developed for survey- ing, engineering, archeology, and medical purposes. Laser scanners range widely in portability, depending on the intended use of the scanner. Some laser scanners (including those designed for documenting biological material or smaller objects) can be quite large in size. For example, 3dMD’s Cranial System requires a dedicated room to accommodate the frame and 5-camera system (http://www.3dmd.com/3dmdcranial.html, accessed July 5, 2010). Some mid-sized scanners such as Eyetronic’s FaceSnatcher (approximately US$125,000) are not portable enough to be easily taken into the field. There are a variety of high-resolution hand-held scanners on the market. Hand-held models usually consist of a single or double headed laser scanner, a transmitter that serves as datum to orient the object and provide scale, and a software package to capture and manipulate the images (see Fig. 1). An optional stylus unit allows for specific point information capture and the software includes a ‘‘mark with mouse’’ feature that facilitates measurement, image comparisons, and highlights specific features for use in court presentation. The images can then be exported to a variety of 3-D image manipulation software packages such as 3DS Max, Maya, AutoCad (Autodesk), Rhino, or Blender (http://www.blender.org, accessed July 2, 2010). The hand-held units fit in a briefcase for easy transport and require only a power source and a laptop with the appropriate software. Creaform 3D (Levis, Quebec, Canada) offers a wide selection of hand-held scanners in the HandyScan 3D family, ranging from the entry level UNIScan to the VIUScan, which captures 3-D data in full color. The Leica T-Scan TS50 (Knowhill, Milton Keynes, U.K.) offers a scanner that is able to capture a single object up to 30 m in size. With the increase in laser scanning accuracy, current scanners have the ability to go from part-to-CAD ready, which allows for reverse engineering and advances analyses. Pricing is dependent on the level of accuracy and resolution, whether the device captures data in color, and whether the scans are limited to small parts or larger volume objects. Unlike traditional digital images, in which resolution is measured in dpi, 3-D laser scan images are saved as microns, which are a measurement of space, rather than pixels. Therefore, direct transla- tion of image resolution to current industry standards is not appro- priate. However, image quality and resolution of a laser scan far 1 School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool L3 3AF, U.K. 2 Center for Human Morpho-Informatics Research, University of South Florida College of Medicine, 12901 Bruce B. Downs Blvd., MDC 11, Tampa, FL 33612. Received 7 July 2010; and in revised form 23 Nov. 2010; accepted 26 Nov. 2010. J Forensic Sci, 2011 doi: 10.1111/j.1556-4029.2011.01915.x Available online at: onlinelibrary.wiley.com Ó 2011 American Academy of Forensic Sciences 1