3D Documentation Of A Clandestine Grave: A Comparison .
ArticleOriginal Article3D Documentation of a Clandestine Grave: AComparison Between Manual and 3D Digital MethodsVictoria Berezowski1 MSc, Jason J. Keller2 & Eugene Liscio1 PEng1University of Toronto Mississauga, Ontario, Canada2NCIS Office of Forensic Support, Great Lakes, Illinois, USAAbstractArticle InformationThe purpose of this research was to compare manual and 3D digital methods for documentation of aclandestine grave located at the University of Toronto Mississauga. Measurements were taken using manualtrilateration as well as digitally using a total station and a terrestrial laser scanner. Comparisons were madebetween each method using 14 landmarks on a buried skeletal cast. Twenty-five measurements were takenacross the 14 landmarks using Rhino, a 3D modelling software, as well as FARO Scene. These measurementswere compared and found an average difference of 1 mm between the total station and the laser scannermeasurements, 10 mm between the total station and manual measurements, and 10 mm between thelaser scanner and manual measurements. The results provide investigators with an alternative method ofclandestine grave documentation that can be more precise as well as being time and personnel efficient onscene.Received:25 June 2018Revised:10 October 2018Accepted: 1 November 2018Published: 10 December 2018Keywords: clandestine grave, trilateration, total station, laser scanner, crime scene survey, crime scenereconstruction, forensic scienceAuthor contact:eliscio@ai2-3d.comIntroductionCases that involve buried skeletal remainsincur many additional challenges, comparedto traditional death investigations. If the caseinvolves buried human remains, it is the job ofthe investigators to excavate and document thegrave, its contents and the surrounding area, incoordination with the medical examiner’s orcoroner’s office [1, 2]. Law enforcement officerscan choose to rely on the expertise of a forensicanthropologist if the case requires it [1, 2].To document the grave, forensic practitionerstraditionally employ hand mapping techniquessuch as trilateration, triangulation, and baselinemethods using measuring tapes, line levels,J Assoc Crime Scene Reconstr. 2018:22Citation: Berezowski T, Keller J, LiscioE. 3D Documentation of a Clandestine Grave: A Comparison BetweenManual and 3D Digital Methods.J Assoc Crime Scene Reconstr.2018;22:23-37.and plumb bobs [3]. Although these manualmethods are accepted by the court system andforensic professions as accurate, easy to perform,and cost effective; they are time consuming,personnel intensive, and give a limitedvisualization of the grave. With the emergenceof 3D mapping technologies such as terrestriallaser scanning and hand-held structured lightscanners, the process of grave documentationcould be drastically improved.A clandestine grave or burial can be definedby the process of concealing a body in theground [3, 4, 5, 6]. Crime scenes wherein aclandestine grave is located are unique in that23www.acsr.org
they require a specialized set of techniquesand tools to properly excavate, document andrecover the human remains, and associatedevidence buried within the grave. Unlikedocumenting a traditional crime scene in aresidence or an outdoor scene where contextualinformation can be preserved throughoutthe documentation process, as soon as theclandestine grave excavation begins, there is animmediate risk of destruction for contextualinformation within the grave [3]. Soil mustbe removed from the grave, in a controlled,methodical manner, to ensure that all evidenceis properly documented and collected.A large amount of investigative informationcan be recovered from a clandestine graveif properly excavated and documented.Alternatively, when a clandestine grave isimproperly documented and excavated, cluesabout the sequence of events, body position, andvaluable pieces of evidence may be lost forever.Once a piece of evidence is removed from thegrave, its contextual value is lost, meaningits relationship to other items in the grave aswell as its depth can no longer be accuratelydetermined and subsequently documented [3,4, 5]. Therefore, proper training in followinga sound methodology for grave excavationis paramount to the integrity of the evidencewithin a grave.A proper documentation method toaccurately and efficiently capture the specificlocation in three-dimensional space of itemswithin a grave and the context surroundingthose items is as important as a proper graveexcavation technique. Depending upon thecircumstances under which the human remainswere placed in the grave, investigators relyheavily on the evidence found within the graveas well as the position in which the body wasplaced to reconstruct the events surroundingthe burial. Valuable evidence can includeweapons, clothing, cigarette butts, jewelry,identification, ligatures, and biological material.As an example, if a three-dimensional footwearimpression is discovered below the body, onemay infer it was created by the individual whodug the grave and therefore becomes a valuablepiece of the reconstruction and subsequentidentification of a suspect.The relationship between the body’s head,torso, and extremities may shed light on themanner in which the body was placed into thewww.acsr.org24grave and is largely dependent upon the size ofthe grave, as well as the strength and numberof individuals involved with the burial [3]. Theposition of the body inside the grave can alsohighlight pertinent case information such aswhether or not the individual’s hands or feetwere bound. For example, if an individual wasfound with their hands behind their back, itcan be inferred that the individual was bound,as ligatures (depending on the material used)tend to decompose faster than skeletal remains.Likewise, if there was any dismemberment,either pre-burial or post-burial, the positionof the remains within the grave may helpreconstruct these events [7]. Body position mayalso tell whether the burial is a primary burial(i.e. the body was placed within the grave andleft undisturbed) or a secondary burial (i.e. thebody was moved from one grave to another aftera period of decomposition) [3, 6]. If the remainsare found disarticulated, an investigator may beable to draw the conclusion that the burial isa secondary burial. Hence, the importance ofproperly documenting the remains’ positionwithin the burial is of great importance andcould be lost if the remains are not properlydocumented.This study compared manual and 3D digitalmethods for documenting a clandestine gravecontaining a casted set of human remains.More specifically, this research comparedmanual measurements of a skeleton usingtrilateration and digitally using a FARO X330laser scanner and a Sokkia 530 R3 total station[8, 9]. The results of each measurement methodwere compared and analyzed in an effort todemonstrate which method might providethe greatest benefits in ease of use, accuracyand thoroughness of documentation, requiredpersonnel, and visualization capabilities.3D Technologies for ClandestineGravesManual measurement methods have servedcrime scene investigators for years andcontinues to be a low cost and simple meansof documenting crime and accident scenes.However, with simplicity comes some limitationson what can be documented since usingmeasuring tapes requires coming into contactor close proximity to all items of evidence andpoints being measured. Thus, there is always aJ Assoc Crime Scene Reconstr. 2018:22
risk that evidence may be contaminated and/or disturbed. There are also limitations onhow accurately or precisely a piece of evidencemay be measured on sloped or irregularterrain. Using tape measures, plumb bobs,and string are suitable on indoor crime scenesand smaller outdoor scenes with flat surfaces,simple geometry and open spaces. However,there are many situations where it is practicallyimpossible to give an accurate representationof a crime scene from manual methods dueto the complexity of the environment. Forexample, evidence located on the side of a cliffor steep slope would be difficult to accuratelydocument. The same can be said in areas withdense vegetation or obstructing objects. Thisis perhaps one of the greatest advantages whenusing 3D technologies such as laser scanners,structured light scanners and photogrammetry.The ability to reach and measure surfaces to ahigh degree of accuracy and repeatability overgreat distances is highly beneficial.Total StationThe total station has been in use on crimeand accident scenes since the 1990s [10]. Thisinstrument is a laser-based device that sendsout modulated laser signals which are reflectedback to a receiver. The 3D position of a pointcan be calculated and reported directly to theoperator. The unit is in effect two instrumentsin one with the electronic distance measuring(EDM) unit and the theodolite (to measure thevertical and horizontal angles). The obtaineddata is collected in spherical coordinates andautomatically converted into 3D Cartesianused by CAD programs.One of the benefits of the total station isthat it can be used over very long distances(well over 1000 m) using a target prism andpole. The operator places the bottom tip of thepole over or next to any piece of evidence andonce the pole is leveled, a measurement can betaken. Traditionally, the total station requirestwo people to operate (one to aim the unit andone to hold the prism pole), however there areseveral models available which are robotic andcan be operated by one person that controlsboth the unit and the prism pole level. Roboticunits can automatically track the prism poleand follow the operator as they move abouta crime scene. That being said, most moderntotal stations allow for reflectorless operationJ Assoc Crime Scene Reconstr. 2018:22which is a “point and shoot” operation. Theoperator looks through the eye piece and placesthe crosshairs on an object that they wish tomeasure. Once aligned, a sample measurementcan be taken. Reflectorless measurements oftenhave less range (roughly 500m or less) andcan be subject to greater error because of themethod being used to measure the distance.Total station manufacturers often provideerror calculations based on the method ofmeasurement in their respective specificationsheets. Although the reflectorless total stationmay incur errors over larger scenes, it removesthe additional variable of a rodman holding apole unsteady and allows for measurements tobe made at elevated positions (e.g. top of poles,upper floors of buildings).The data captured with a total station isoften restricted to distance and positional data.This data shows up as a table of points whichcan be exported to other software for creatingplan drawings or sketches. The main limitationof using the total station is that capture timeis relatively slow and documentation can berather tedious. Only one point at a time canbe captured and then the instrument needs tobe targeted to the next position. As a result,areas where there are a lot of densely packedand complex pieces of evidence can be timeconsuming or simply impossible to capturewith a high degree of detail. In addition, thesetup time and process of moving a total stationaround the corner of a building or through adoorway to access areas that are out of the lineof sight can be tedious and time consuming.Tight spaces with many obstructions meansthat the total station must be in the direct lineof sight of evidence or at least the prism shouldbe visible to the total station.The Laser ScannerThere is no other instrument in existence todaywhich can capture as many measurements/points of a crime scene in as little time as the laserscanner. Millions of tightly packed points canbe captured of a scene in what is referred to as a“point cloud” which gives a representative andaccurate view of the geometry or environmentin a 360 window from the perspective of thelaser scanner, with the only missing informationbeing directly under the scanner. By aligningmultiple scan positions together like pieces ofa puzzle, an entire indoor or outdoor scene can25www.acsr.org
be aligned together into a full 3D environment.As a result, more can be done with laser scannerdata than when using manual measurements ora total station.The laser scanner uses LiDAR (LightDetection and Ranging) technology at its coreand there are different modes of operation. Atthe most basic level, the laser scanner operatesin much the same fashion as the total station.The laser scanner sends out multiple signals toa surface and once these signals are reflectedback to the receiver, it can calculate the anglesand distance [11]. Unlike the total station, thelaser scanner is fully automatic and does notrequire the operator to aim or target a specificobject. The laser scanner rotates to capture theenvironment in a 360 fashion and has theadditional option of capturing photographs.When multiple scan positions are taken,there are different methods in which the scanscan be aligned or “registered.” Registration isa method of alignment where all the scans arebrought into the same coordinate system toreflect and provide an accurate representationof the scene. There are basically two methodsof registering scans together using specialtargets or simply the existing geometryin the environment. The use of spheres orcheckerboard targets is a customary practiceand well suited for clandestine graves sincethe area being documented may be relativelysmall with considerable foot traffic in the areawhich can block the scanner from seeing thefull environment. In addition, documenting anenvironment which is subject to rapid change(such as melting snow or moving vegetation)can benefit from the use of fixed and stationaryregistration targets. Stationary targets arebeneficial because the software can detect thetarget locations as found in each scan. However,it should be noted that targets must be fixedon rigid structures. Targets must not movethroughout the excavation process and hence,must be semi-permanent and resistant to theelements for an extended period of time.The second type of registration, targetlessregistration, does not require the use of anyfixed targets; however, it does require thatthere is sufficient overlap and unique geometryin the scene. Wide open areas which are voidof any vertical structure like an open field ora flat, sandy beach are not the best optionsfor targetless registration. In addition, areaswww.acsr.org26with dense vegetation are not well suited forthis type of registration either since movingthe scanner only a short distance could createa completely different environment withlittle to no overlap from the previous scanposition. However, the benefit of this typeof registration is that it is minimally invasiveand saves time in the placement of the targetspheres or checkerboard targets. In most areassuch as an indoor apartment or outdoor areawhere there are buildings and other structuresaround, targetless registration works very well.Ultimately, either method could be used forsuccessful documentation depending on theenvironment and application.Upon successful registration of theindividual scans, the scene can be visualized ina realistic fashion. Virtual tours, 3D prints, andeven virtual reality are all possibilities when thedata has been captured using a laser scanner.Additionally, diverse types of analysis can beperformed using laser scanner data. Crosssections, deviation analysis, bullet trajectories,bloodstain patterns, volume calculations,and witness perspectives may all be tested oranalyzed. Although these analyses have beendone for decades using total station or manualmeasurement data with the 3D generatedcomputer models, the arrival of the laserscanner has made them easier to perform.Structured Light ScannersStructured light scanners represent a group of3D technologies which use a known patternprojected on a surface so that its geometry may becaptured. At the very minimum a projector anda camera with a known position to one anotherare used, but there are systems which work withmultiple cameras and varying types of patternsto provide more accurate data. Structured lightscanners are often used for smaller scale scenesor smaller pieces of evidence. Many of thesesystems have been incorporated into hand helddevices which can be moved about an object aslarge as several meters or as small as a suspect’sshoe or weapon. These instruments are oftenquite fast in terms of their capture time andthey can range in accuracy from the centimeterto sub-millimeter scale.Two types of structured light scanners arewhite light and laser light scanners. White lightscanners use traditional bulbs or LED lightsto emit rapidly alternating patterns while laserJ Assoc Crime Scene Reconstr. 2018:22
light scanners often use a projected series ofdots which is in the infrared, non-visible range.As a result, one limitation of each technologyis that they perform poorly in sunny or verybright conditions since the camera must resolvethe emitted infrared pattern against the sun’sambient light. When working in direct sunlight,data may be incompletely captured or in moreextreme cases, impossible to capture unlesssome cover or shade is provided. The differencebetween the skeletal remains being capturedwith a structured light scanner with and withoutcover can be seen in Figure 1.Speed of capture is of primary benefit sincea hand held structured light scanner can bedeployed each time a new piece of evidence isfound. When considering a clandestine grave,a newly excavated layer may contain someevidence which, in a matter of a few minutes,can be documented as a 3D data set and achronological record can be stored indefinitely.Similar to the laser scanner mentioned above,3D data allows for diverse ways of analyzing andpresenting evidence either in a recreated physicalform or as a virtual model. The smaller scale andrapid capture with hand held structured lightscanners integrates well with other technologiessuch as the total station, laser scanner, andphotogrammetry.PhotogrammetryModern day photogrammetry is attractive tocrime scene investigators because of the relativesimplicity of use and automated processingof data. The basic premise is that multiple,overlapping photographs of a scene or pieceof evidence may be input into software andprocessed to create a digital and photorealistic3D model. This is especially useful in caseswhere color, staining, or marking is visible butnot as a protruding, geometric mark, such as soilstaining on uncovered skeletal remains.Commercial drones have provided aresurgence and interest in photogrammetrybecause of the relative ease of access to higherelevations and the possibility of creating largescale digital models of entire crime scenes. Incomparison to laser scanning, photogrammetryis typically much faster in terms of thedocumentation time since all that is necessaryis a series of strategically placed overlappingphotographs. Post-processing on a computeris often intensive but this is seen as less of aproblem since the loss of time is off site and notwhile the scene is being processed.With respect to clandestine graves, acombination of photogrammetry and othertechnologies is easily employed and it is possibleto combine 3D data from various sources.Figure 1: Comparison between the resulting 3D models using the Dot Product handheldstructured light scanner. Left: Captured when the grave was covered (from sunlight) with apop up tent and tarps; Right: Captured without anything covering the grave.J Assoc Crime Scene Reconstr. 2018:2227www.acsr.org
Photogrammetry can be employed immediatelyaround the grave location and if overlappingphotographs are taken in a “ring” around thegrave, they are easily processed to create a full3D model. Similarly, video from mobile phonesor tablets may also be employed to capture agrave. One would only need to walk aroundthe grave and by pointing the camera in thedirection of evidence, the resultant framesare already overlapping and
across the 14 landmarks using Rhino, a 3D modelling software, as well as FARO Scene. These measurements were compared and found an average difference of 1 mm between the total station and the laser scanner measurements, 10 mm between the total station and manual measurements, and 10 mm between the laser scanner and manual measurements.
Capillary Electrophoretic Analysis of Clandestine Methamphetamine Laboratory Evidence Three goals were outlined for this project: 1) To develop capillary electrophoresis methods that can be used to assist in the identification
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