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 difficult 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.
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ABSTRACT: Non-contact surface mapping at a distance is interesting in diverse applications including industrial metrology, manufacturing, forensics, and artifact documentation and preservation. Frequency modulated continuous wave (FMCW) laser detection and ranging (LADAR) is a promising approach since it offers shot-noise limited precision/accuracy, high resolution and high sensitivity. We demonstrate a scanning imaging system based on a frequency-comb calibrated FMCW LADAR and real-time digital signal processing. This system can obtain three-dimensional images of a diffusely scattering surface at stand-off distances up to 10.5 m with sub-micrometer accuracy and with a precision below 10 µm, limited by fundamental speckle noise. Because of its shot-noise limited sensitivity, this comb-calibrated FMCW LADAR has a large dynamic range, which enables precise mapping of scenes with vastly differing reflectivities such as metal, dirt or vegetation. The current system is implemented with fiber-optic components, but the basic system architecture is compatible with future optically integrated, on-chip systems.Optics Express 10/2014; 22(21):24914-28. · 3.53 Impact Factor
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ABSTRACT: Human decomposition is a dynamic process that is influenced by both abiotic and biotic factors. Measuring these influences, in particular abiotic factors, on the decomposition process is often a challenge for scientists. Recently, researchers have turned to the use of advanced remote sensing technologies in forensic investigations. In this study, a new methodology is described that utilizes precise 3D images captured using terrestrial laser scanning (TLS) to calculate total solar irradiance on a cadaver in a partially forested environment. To test this new measurement approach under actual field conditions, three cadavers were placed in an outdoor environment to decompose. Laser scans were taken the day of placement and used to calculate the total solar irradiance at time points of 24 h, 1 week, and 1 month from placement. The results show that as time progresses, different cadavers at the field site and different areas of the same cadaver receive varying amounts of solar irradiance. The modeling based on these laser scans can be used to create predictive images of solar irradiance that may provide researchers with a new tool to help quantitatively assess the effect of solar irradiance on a cadaver ecosystem.Deutsche Zeitschrift für die Gesamte Gerichtliche Medizin 05/2014; · 2.69 Impact Factor
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ABSTRACT: The 3D acquisition of object structures has become a common technique in many fields of work, e.g., industrial quality management, cultural heritage or crime scene documentation. The requirements on the measuring devices are versatile, because spacious scenes have to be imaged with a high level of detail for selected objects. Thus, the used measuring systems are expensive and require an experienced operator. With the rise of low-cost 3D imaging systems, their integration into the digital documentation process is possible. However, common low-cost sensors have the limitation of a trade-off between range and accuracy, providing either a low resolution of single objects or a limited imaging field. Therefore, the use of multiple sensors is desirable. We show the combined use of two low-cost sensors, the Microsoft Kinect and the David laserscanning system, to achieve low-resolved scans of the whole scene and a high level of detail for selected objects, respectively. Afterwards, the high-resolved David objects are automatically assigned to their corresponding Kinect object by the use of surface feature histograms and SVM-classification. The corresponding objects are fitted using an ICP-implementation to produce a multi-resolution map. The applicability is shown for a fictional crime scene and the reconstruction of a ballistic trajectory.Sensors 04/2014; 14(4):7563-79. · 2.05 Impact Factor
Debra A. Komar,1Ph.D.; Stephanie Davy-Jow,1Ph.D.; and Summer J. Decker,2Ph.D.
The Use of a 3-D Laser Scanner to Document
Ephemeral Evidence at Crime Scenes and
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.
Proper documentation of physical evidence at both crimes scenes and postmortem examination is crucial for downstream analysis,
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
1School of Natural Sciences and Psychology, Liverpool John Moores
University, Liverpool L3 3AF, U.K.
2Center 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
J Forensic Sci, 2011
Available online at: onlinelibrary.wiley.com
? 2011 American Academy of Forensic Sciences
exceeds that of traditional digital photography. Scanning time per
object is minimal and dependent on the number of separate passes
or scans of the object with the hand-held wand.
The images contained in this article were generated using a Pol-
hemus FastSCAN Scorpion two laser hand-held unit (Colchester,
VT). The unit was purchased in 2009 and the total price, including
necessary software, was approximately £12,000 (US$18,000).
Those with tight budgetary constraints or working in remote areas
may even be able to fashion their own laser scanner from materials
available at standard hardware stores or home centers (see, e.g.,
accessed July 2, 2010). Those utilizing noncommercial or home-
made scanners should check that there are no legal impediments to
introducing evidence generated by such units in their relevant
Potential Scenarios in Which to Use 3-D Laser Scanning
Although not comprehensive or exhaustive, the following list
provides some indication of the possible field and laboratory sce-
narios that might benefit from the use of 3-D laser scanning as a
supplement to standard documentation.
• Clandestine graves. Laser scanning can be used to capture fea-
tures of the grave walls, including shovel marks for future com-
parisons against suspect tools, as well as footprint or tool
impressions on the grave floor. Because the hand-held laser
scanners are capable of recording objects of any size (limited
only by file storage capacity), it is possible in theory to scan the
entire grave, with remains in situ, as a supplemental source of
documentation. Only the transmitter (a small unit) would need
to be placed within the grave, to serve as datum and orient all
subsequent laser scan passes. With proper use of the equipment,
the resolution of the image remains constant for the entire
• Footprints, tool marks, and other impressed artifacts. Prior to
any attempts to cast the feature using conventional methods, a
laser scan of the impression can be generated and used in subse-
quent comparisons against objects suspected of creating the
impression (see Figs 2 and 3). The 3-D images generated of
both the impression and suspect object are then available for
downstream analysis and comparison, as well as for presentation
in court, providing an easily understood visual demonstration
tool for lawyers and juries.
• Impressions in materials resistant to standard casting methods.
Such impressions include tool, teeth or fingerprint marks in soft,
perishable or frozen food items (see Fig. 4) as well as footprints
or other impression in snow, powder, or other media unsuitable
for casting. A recent case investigated by one author (DK) illus-
trates the potential offered by laser scanning. A homicide victim
was buried in a remote location in a grave in which the perpetra-
tor had added a layer of powdered lime, mistakenly believing it
had the same destructive properties as caustic lye. The victim
was deposited face down in the grave, and the full facial features
were captured in the lime in a naturally occurring ‘‘death-mask.’’
Photographs of the impression failed to capture the image, and
attempts to stabilize the lime powder as a cast were unsuccessful.
Subsequent attempts to introduce a casting material into the
impression destroyed the lime base and the information was lost.
Had a laser scanner been available, an accurate 3-D image of the
face could have been rendered without damaging the artifact.
• Fire scenes. Burned human remains are exceptionally friable,
and their collection, transport, and analysis require special
handling (see, e.g., Fairgrieve ). Of particular concern is evi-
dence of trauma in burned and degraded remains, which can be
damaged or lost during exhumation or recovery. In situ laser
scanning can capture images of friable remains that will degrade
upon collection and handling, providing 3-D models of remains
FIG. 2—A 3-D laser scanner image of a footprint impression in fine
FIG. 1—The Polhemus FastSCAN Scorpion 3-D laser scanner. The
double headed hand-held scanner is in the foreground, with the transmitter
directly behind. The image on the screen is of a buried skull scanned in
FIG. 3—A 3-D laser scanner image of the suspect shoe. Manipulation of
the images in Figs 2 and 3 with an imaging software permits direct
comparison and provides a demonstration tool for court purposes.
JOURNAL OF FORENSIC SCIENCES
• Mass graves in human rights investigations. Laser scanners can
be used to capture tire, bucket teeth, and other impressions asso-
ciated with heavy equipment used to form the grave, as well as
shovel marks and other impressions visible in the grave walls.
3-D images can also be rendered of features that may be dis-
turbed or dissociated during the recovery process, including
blindfolds and ligatures, ephemeral personal effects such as
degraded photographs, identification cards, or decomposing
clothing, or biological materials such as food stuffs, plant
remains, or other perishable items. Skulls with gunshot wounds
or other traumatic defects can be scanned in situ, allowing for
easy reconstruction of the fragments of the skull in the
• At postmortem. In addition to standard photographic protocols,
capturing 3-D images using a laser scanner should be consid-
ered in cases involving bitemarks to skin or other tissues (4),
skin impressions such as ligature marks or tool imprints, kerf
analysis of sharp force injuries (8), and skeletal cranial remains
for use in facial reconstructions or osteological analysis (5,7).
Scanning the texture of an organ at autopsy can document path-
ological conditions such as cirrhosis of the liver, which causes
lesions that are difficult to document well in 2-D photographs.
A final novel use of the laser scanner involves cases in which
visual identification of the remains by a family member is
required. The laser scan can be used in lieu of viewing either a
photograph or the actual remains to ease the anxiety of the
next-of-kin or in cases in which mild decomposition or other
postmortem changes may render the remains disturbing to the
family members, as such changes can be modified or removed
on the 3-D image prior to viewing by the family.
Advantages of the Technology
Advantages of laser scanners over other 3-D imaging technolo-
gies (such as computed tomography [CT] or magnetic resonance
imaging [MRI]) include relative cost of the initial equipment and
subsequent maintenance, speed of image generation, portability,
equal or greater spatial resolution of models generated, and that the
low-energy light used by laser scanners is nonhazardous to the
operator and biological specimens under examination (5,10). One
final advantage of laser scanning over CT or MRI is that laser
scanning is user friendly and easily mastered with minimal training,
typically provided by the scanner’s commercial supply house as
well as on-line user tutorials.
The benefits of laser scanning over conventional photography
include the potential to generate accurate, reproducible measurements
from the 3-D image (5); information discernible in three but not two
dimensions; the ability to manipulate 3-D images using alternative
software programs (including the potential for animations or other
demonstrations for court purposes); and the ability to reconstruct
missing elements from partial evidence, such as filling in absent or
damaged cranial bones for the purposes of a computer generated
facial reconstruction. Ambient lighting also has no impact on the per-
formance of the scanner, unlike traditional photography. The image
is generated by a series of laser beams, which operate independent of
scene lighting. Unlike photographs used for video superimposition or
other identification or comparative techniques, which must be shot in
the same orientation as the suspect image, the 3-D images generated
by laser scanner can be manipulated into any position. Finally, the
images generated by 3-D laser scanner can be saved in a variety of
formats, making them easily shared with colleagues and consultants
via email, should second opinions or assistance be needed or for dem-
onstration purposes in court.
Limitations of the Technology
While the advantages gained by supplementing photography and
other traditional methods of documentation with 3-D images are
considerable, the use of the laser scanner may be limited by a num-
ber of factors. First, the unit requires a power source. Although
generators, car adaptors, and other remote power sources offer
potential, some scenes are sufficiently remote, dispersed, or other-
wise inaccessible as to render this a valid constraint. Second, the
cost of the unit may be outside of the budgets of smaller law
enforcement units or medico-legal death investigators. Third, incor-
rect use of the equipment can produce artifacts on the images that
can be misinterpreted or misidentified. Proper training and mainte-
nance of the equipment typically overcomes this problem. Fourth,
certain types of evidence may not be captured by the laser scanner.
For example, an attempt by the authors to image very faint sharp
force kerf defects on human rib bones was unsuccessful because of
the size and limited visibility of the objects. Some metallic objects,
such as a mirror or highly reflective surface, can cause interference
with the scan. Highly reflective surfaces may pose problems but
can be powder-coated. Some lower end hand-held scanners do not
capture complex geometries such as the human skull or mandible
well because of inferior resolution quality. There are some hand-
held units such as the HandyScan 3D that require small targets be
placed on the object being scanned to capture surface detail. Often
these targets are small reflective stickers that are affixed to the
surface. These stickers can be destructive and, in most forensic
contexts, would be prohibited as it modifies the object under exam-
ination. Finally, those wishing to use 3-D images as evidence in
court should review all statutes pertaining to the introduction of
digital images within the relevant jurisdiction, particularly those
relating to the subsequent manipulation of such images (i.e., anima-
tion) for demonstration purposes. To the authors’ knowledge, 3-D
laser scan images have not yet been introduced in a court of law.
FIG. 4—An example of a laser scan of an impression embedded in media
unsuitable for traditional casting. The image is of a bitemark registered in
a chocolate coated, soft caramel bar with oatmeal flake base. This image
can then be compared to laser scans of suspect dental casts.
KOMAR ET AL. • LASER SCANNER AND EPHEMERAL EVIDENCE
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Additional information—reprints not available from author:
Summer J. Decker, Ph.D.
Center for Human Morpho-Informatics Research
Department of Pathology and Cell Biology
University of South Florida College of Medicine
12901 Bruce B. Downs Blvd, MDC 11
Tampa, FL 33612
JOURNAL OF FORENSIC SCIENCES