The Application of Remote Sensing for Detecting Mass Graves: An Experimental Animal Case Study from Costa Rica*

Abstract

Detection of mass graves utilizing the hyperspectral information in airborne or satellite imagery is an untested application of remote sensing technology. We examined the in situ spectral reflectance of an experimental animal mass grave in a tropical moist forest environment and compared it to an identically constructed false grave which was refilled with soil, but contained no cattle carcasses over the course of a 16-month period. The separability of the in situ reflectance spectra was examined with a combination of feature selection and five different nonparametric pattern classifiers. We also scaled up the analysis to examine the spectral signature of the same experimental mass grave from an air-borne hyperspectral image collected 1 month following burial. Our results indicate that at both scales (in situ and airborne), the experimental grave had a spectral signature that was distinct and therefore detectable from the false grave. In addition, we observed that vegetation regeneration was severely inhibited over the mass grave containing cattle carcasses for up to a period of 16 months. This experimental study has demonstrated the real utility of airborne hyperspectral imagery for the detection of a relatively small mass grave (5 m(2)) within a specific climatic zone. Other climatic zones will require similar actualistic modeling studies, but it is clear that the applications of this technology provide the international community with both an early detection tool and a tool for ongoing monitoring.

Preliminary results of sequential monitoring of simulated clandestine graves in Colombia, South America, using ground penetrating radar and botany

“…Discovered clandestine graves of victims have been reported to be isolated [3,4] , co-mingled and mass burials [5], and in a variety of burial styles, depths below ground level and depositional environments [3][4][5]. Such numbers of victims has been reported elsewhere globally, for example, in 19 th Century Irish mass burials [6], USA race riot victims [7], Spanish Civil War mass burials [8,9], World War Two burials [10,11], in post-WW2 Polish repression mass burials [12], the Northern Ireland 'Troubles' mostly isolated burials [13], the 1990s Balkan wars mass burials [14,15], and sadly in active civil wars with both isolated and mass burials [16].…”

“…Current forensic search methods to detect both isolated and mass clandestine burials of murder victims are highly varied and have been reviewed elsewhere [17,18], with best practice suggesting a phased approach, moving from large-scale remote sensing methods [19] down to initial ground reconnaissance [20] and control studies before full searches are initiated [21,22). These full searches have also involved a variety of methods, including forensic geomorphology [20], forensic botany [23,24] and entomology [25,26], scent-trained search dogs [27,28], physical probing [29][30][31], thanatochemistry [32][33][34] and near-surface geophysics [35][36][37][38][39][40][41][42].…”

Validating the Remotely Sensed Geography of Crime: A Review of Emerging Issues

“…As other authors have shown, "satellite imagery highlights the spatial footprint of human actors in very real and compelling ways" [14][15][16]. Here, we review the literature that discusses how satellite and airborne technologies have been used in the active detection of felony cases of drug production, smuggling and extra-legal migrations.…”

Hyperspectral imaging for non-contact analysis of forensic traces

“…A forensic science application of remote sensing technology was demonstrated by Kalacska et al [53], who used airborne HSI for the detection of mass graves. Analysis of the spectra using Minimum Noise Fraction transform showed a clear separation between an experimental grave, a refilled empty grave, grass and forest.…”