Mass grave complexity affects estimation of minimum number of individuals

Mass grave complexity effects on the minimum number of individuals estimation Igor Vaduvesković & Marija Djuric Forensic Science, Medicine and Pathology ISSN 1547-769X Forensic Sci Med Pathol DOI 10.1007/s12024-019-00186-3 1 23 Your article is protected by copyright and all rights are held exclusively by Springer Science+Business Media, LLC, part of Springer Nature. This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to selfarchive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com”. 1 23 Author's personal copy Forensic Science, Medicine and Pathology https://doi.org/10.1007/s12024-019-00186-3 ORIGINAL ARTICLE Mass grave complexity effects on the minimum number of individuals estimation Igor Vaduvesković 1 & Marija Djuric 1 Accepted: 11 September 2019 # Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract This study analyses the accuracy of the minimum number of individuals (MNI) estimation in the context of commingled human remains recovered from secondary mass graves related to the war in Bosnia in 1995. It is based on data from five secondary mass grave sites of different sizes and different numbers of unassociated body parts. The study is centered on a comparison of MNI estimation from original excavations with the actual number of individuals buried in particular graves, obtained via DNA identification of excavated remains. The aim was to investigate how the complexity of a mass grave reflects on MNI estimation accuracy. In order to quantify mass grave complexity (level of commingling), a ratio between complete bodies and isolated body parts from the same context was introduced. Results show that, in the secondary mass graves involved in the study, MNI estimation inaccuracy varies in the range from 54% to 513% depending on the size of the grave itself and the amount of “loose elements” distributed in it. Correlation between MNI inaccuracy and body to body parts ratio shows a strong relationship indicating that MNI (in)accuracy is largely dependent on the number of loose elements related to complete bodies from the same context. Keywords Forensic science . Forensic anthropology . Minimum number of individuals . Secondary mass graves . Commingled human remains Introduction The minimum number of individuals (MNI) technique, by definition, shows what the minimal number of specimens represented in assemblages is, not the real number or necessarily the closest value to the real number, but the smallest number. However, if we want to use MNI as a bench mark for further forensic investigation, large discrepancies between MNI and the real number of individuals in the assemblage make MNI calculation less useful and inaccurate. Minimum number of individuals estimate, as a quantitative technique that involves determining the most commonly occurring skeletal element of a taxon in an assemblage, was * Marija Djuric [email protected] Igor Vaduvesković [email protected] 1 Laboratory for Anthropology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, Dr Subotica 4/2, Belgrade 11000, Serbia first applied in paleontology by Stock and Howard [1, 2]. Later, MNI was used in zoological and zooarchaeological studies from the middle of the last century [3, 4]. The technique has constantly evolved, particularly adding a probability calculation to account for the variations in bone recovery [4, 5]. Further developments in the MNI estimation included the use of osteometry for bone elements matching in order to separate individuals from commingled deposits [6]. Commingled skeletal remains refer to the mixing of whole or fragmented skeletal elements of two or more individuals in a single context [7]. Establishing MNI is the most important venture in any commingled assemblage [8, 9] and is often the first task of an investigation [10]. An accurate estimate is important for scientific, legal and ethical reasons [5–7, 11, 12]. In forensic practice MNI is important because it estimates the size of the population represented in the grave which may indicate the identity of the group of victims and have an impact on an ongoing investigation process. For example, if there is information that different group of people containing various numbers of individuals were killed and buried in mass graves, the field MNI estimation should immediately imply what group of Author's personal copy Forensic Sci Med Pathol killed individuals is in question. Also, accurate MNI prior to the end of fieldwork serves to correctly assess the amount of additional forensic work needed, facilities required and associated expenses in further investigation. Although MNI has been used in routine work for decades, according to our knowledge there are no papers published on the topic of MNI estimation inaccuracy in secondary mass graves. Even in the commingled contexts, not necessarily from secondary deposits, there are no assemblages for which the original number of individuals is known prior to commingling [13]. This issue makes assessing an MNI estimation inaccuracy impossible prior to the application of the DNA identification techniques that have been used in this research for determining the real number of individuals buried. While primary inhumation sites can produce commingling mostly due to taphonomic factors, secondary inhumation sites present a real challenge because commingling is more severe due to the relocation of bodies. According to Jesse and Skinner, a primary inhumation site or the primary deposition is the site at which remains were originally buried [14]. Primary sites have lower rates of commingling. Secondary inhumation sites are sites containing remains that were exhumed from the primary grave and then relocated to a different grave [14]. During the process of redepositing to the secondary grave, remains become severely commingled and disarticulated while smaller bone fragments are often lost. Some sites may contain both primary and secondary inhumations, and are referred to as a multiple deposit interment site these sites are even more commingled due to the disturbance of the original gravesite [14]. Site formation process, especially manner of mass grave deposition such as using heavy machinery (mostly front end loader) for removing bodies from execution site to the primary mass grave, leads to disarticulations of the bodies that cause commingling and possibly deposition of one single individual to different graves. Disarticulation of the bodies can also occur before deposition as a result of the sanitation of the battlefield after combat or because of death incurred by heavy weapons such as mortar, grenades, anti-aircraft gun, tank or minefield in which case even primary graves can show heavy commingling. Furthermore, looting of graves i.e. removing deposited bodies from primary graves to different locations, leads to heavy disarticulations and comingling of the bodies and to situations where body parts of one single individual end up in one or several secondary mass grave locations. Also, various taphonomic processes can lead to disarticulation and dislocation from the original position [15, 16]. All of these factors make MNI estimation harder and leads to inaccurate MNI estimations, particularly in cases of secondary mass graves in which most of the issues mentioned above are commonly observed and proper excavation is particularly challenging. In the context of heavily commingled secondary mass graves from Srebrenica-related cases in Bosnia osteometric matching would not work because of the sheer size of the assemblage and the fact that corresponding bone elements often happen to be located in a different burial location. Even if the above mentioned problem is overcome, osteometry and morphological matching of sides or joints are rendered much less reliable in the case of Srebrenica and similar sites due to the extraordinary homogeneity of the victims (mostly adult males) [17]. To overcome this reassociation issue and achieve identification of individuals scattered between mass graves, DNA samples were taken from excavated cases in order to match bone elements scattered between graves with reference blood samples provided by genetically related family members [18]. Data from this forensic process enabled us to compare MNI estimations from various sites with the results of DNA identification from corresponding sites in order to calculate MNI estimation reliability. Furthermore, discrepancies between MNI and DNA data (MNI inaccuracy) in relation to the amount of disarticulated and isolated body parts will help us to understand how the complexity of a mass grave affects estimation of MNI. In order to quantify the complexity of the mass grave we introduced the ratio between disarticulated/ isolated bones and (mostly) complete bodies. The aim of this paper is to measure the result of factors impacting the size of MNI inaccuracy when dealing with commingled remains in order to determine the basis for an MNI estimation improvement. Materials and methods Human skeletal remains for this study were derived from five secondary Srebrenica related mass grave sites. Sites involved in this study represent secondary mass graves from the exYugoslavia civil war, and were deposited in mid-1995 in Bosnia, at the territory of the present day Republica Srpska. The downfall of former Yugoslavia started in 1991 with the secession of the former Republic of Slovenia and the most severe hostilities took place in Bosnia and Herzegovina lasting from 1992 to 1995 [19]. Shortly after the armed conflict in Bosnia the International Criminal Tribunal for the former Yugoslavia (ICTY) started to excavate mass grave sites, and after 2000 the International Commission on Missing Persons (ICMP) took over the forensic process and the implementation of DNA identifications. Numerous mass graves containing Bosnian Muslim male victims were excavated in the region of Srebrenica. For this study we used five mass graves (Map 1) with available anthropological data and with known secondary site formation processes (bodies relocated from primary locations to other mass graves) [20]. According to the data presented during ICTY prosecutions, the relocation was conducted with Author's personal copy Forensic Sci Med Pathol Map 1 Small portion of the south-east part of Bosnia and Hercegovina (BiH) with marked mass grave sites. Embedded map represents the position of BiH within former Yugoslavia (mass graves marked with red rectangle) and position of former Yugoslavia within Europe. heavy machinery (front end loader) several months after primary deposition. A similar situation, but characterized by less body dismemberment and mixing of body parts, was recorded from Batajnica sites in Serbia, which were also created as secondary mass graves using heavy machinery [21]. The excavation of the sites included in this study was conducted between 2006 and 2008 by the Bosnian Federal Commission for Missing Persons aided by the ICMP. The sites were classified as small, medium or large secondary mass graves, the size refering to the quantity of case numbers assigned during excavation, not to the dimensions of the grave pits. In the ICMP protocol case numbers for human remains get designated as B (body) if they represent a complete body (or at least 75% of the body), BP (body part) for body parts representing upper body parts, lower body parts and other articulated remains of one individual, or GBP (general body part) for isolated bones that did not articulate with any remains in the immediate vicinity. The total cases of human remains are all case numbers (B + BP + GBP) that are assigned to human remains in a particular mass grave. Artifacts were not considered in this study. DNA identification was carried out by the ICMP and the general data about reassociations and identification numbers, arranged by the excavation location names, are publicly available on the ICMP web site [22]. The identification process is based on the comparison of blood samples from family members of the missing and DNA profiles from bone samples recovered from the mass graves. DNA identifications of new identities represent cases of missing individuals identified for the first time in the particular mass grave. DNA reassociation represents cases of individuals whose other body parts, usually designated as BP or GBP, had already been found in other graves. Sites involved in the study are as follows. & & & & Snagovo 04 (SNA04ZVO) had 156 cases of human remains: 92 B, 64 BP, and 0 GBP. MNI is 104 based on the presence of the distal third of right tibia. DNA profiling obtained 88 new identities and 72 re-associations, yielding a total of 160 different individuals (i.e. number of individuals represented in the grave with at least one body part). Cancari Road 08 (KAM08ZVO) contained 340 cases of human remains: 22 B, 318 BP, and 0 GBP. MNI for this site is 84 based on left tibia. 50 new identities were obtained by DNA and 273 re-associations, a total of 323 different individuals (i.e. number of individuals represented in the grave with at least one body part). Cancari Road 04 (KAM04ZVO) contained 393 cases of human remains: 145 B, 218 BP, and 30 GBP. MNI for this site is 189 based on complete right femora. DNA identification obtained 183 new identities and 236 reassociations. Therefore, the number of different individuals represented in the grave with at least one body part is 419. Cancari Road 06 (KAM06ZVO) (Table 1) had 1133 cases of human remains assigned: 29 B, 854 BP and 250 GBP. Author's personal copy Forensic Sci Med Pathol Table 1 Summary table of secondary mass graves cases, DNA identifications, and MNI Site Snagovo 04 C. Road 08 C. Road 04 C.Road 06 C.Road 10 Total cases of human remains B (Bodies) BP (Body Parts) GBP (General BP) DNA new identities DNA reassociations Total DNA-based identifications (new ident+reassociation) MNI 156 92 64 0 88 72 160 104 340 22 318 0 50 273 323 84 393 145 218 30 183 236 419 189 1133 29 854 250 182 1063 1245 203 1344 146 1012 186 378 774 1152 368 & MNI is 203, based on the presence of right tibia. DNA profiling obtained 182 new identities and 1063 reassociations, making a total of 1245 different individuals (i.e. number of individuals represented in the grave with at least one body part). Cancari Road 10 (KAM10ZVO) was represented by a total of 1344 cases of human remains: 146 B, 1012 BP and 186 GBP. MNI for the site is 368 based on two thirds or more of right femur while the number of individuals represented in the grave with at least one body part is 1152 (378 new identities +774 reassociations). New DNA identities usually correspond to largely complete bodies excavated in a particular grave. DNA reassociations are mostly related to small body parts (e.g. lower arm or foot) that are buried in a different grave(s) than the majority of the skeleton. So, the sum of reassociations from all the graves above does not mean that it is the sum of people buried because one person may be represented with many reassociated body parts from different mass graves. Total DNAbased identifications are the sum of new identities and reassociations. Total DNA-based identifications shows us how many cases of different individuals are represented in a particular grave. DNA data are provided from the International Commission on Missing Persons (ICMP) public database [22] and MNI data were obtained during the mass graves excavation process conducted by the ICMP (including, at the time, the first author of this study) in the period 2006 to 2008 (reports available at the Republic of Srpska Center for the Research of War, War Crimes and the Search for Missing Persons). The level of complexity within mass graves may be represented by the amount of unassociated body parts within the Table 2 grave compared to the number of complete bodies in that particular grave. In this study, we introduced a specific proportion: a body to body parts ratio (index of commingling), which represents the quantitative relationship between largely complete bodies and unassociated body parts within a particular burial. The body to body parts ratio is calculated by dividing the number of complete bodies by the sum of disarticulated and isolated elements (B/BP + GBP) from the same context. A smaller ratio value indicates more disarticulated elements in the grave, greater complexity of the site, and possible sites of secondary or tertiary origin. In order to investigate how mass grave complexity affects the minimum number of individuals estimation we calculated MNI inaccuracy by comparing MNI estimation for a particular site derived at the time of excavation with the total number of DNA profiles obtained at a later date for the same site. DNA profiles serve as a reference point representing the real number of individuals buried. In order to get percentages we used the following formula: MNI i n a c c u r a c y = ( ( To t a l D N A - M N I ) / M N I ) ) * 1 0 0 . Discrepancies between the minimum number of individual estimation and the real number of individuals buried (MNI inaccuracy) and the body to body parts ratio were tested for correlation by Pearson product-moment correlation. Results Calculated MNI inaccuracy and the body to body parts ratio of the investigated sites are shown in Table 2 and the correlation between them is presented in Fig. 1. Data shows that more disarticulated body parts and isolated bones compared to complete bodies found in the grave indicate greater MNI estimation inaccuracy. Summary table of MNI inaccuracy and body to body parts ratio calculations Site Snagovo 04 C. Road 08 C. Road 04 C.Road 06 C.Road 10 MNI inaccuracy Body to body parts ratio(B/(BP + GBP)) 54% 1.438 385% 0.069 222% 0.584 513% 0.026 313% 0.122 Author's personal copy Forensic Sci Med Pathol Fig. 1 Linear function of B/BP ratio and MNI inaccuracy. Linear equation: y = a + bx Calculated MNI inaccuracies for different sites varied from 54% to 513%. In order to assess the cause of inaccuracy in MNI estimation we correlated MNI inaccuracies for each site (variable 1 = 54%, 385%, 222%, 513%, 313%) with Body to body parts ratio for each site (variable 2 = 1.438, 0.069, 0.584, 0.026, 0.122) using Pearson’s correlation. Correlation is calculated with EZR (Easy R) software and verified with Origin. Results show strong negative correlation with a correlation coefficient = − 0.922 and a 95% confidence interval. The confidence interval (CI) is −0.995 to −0.214 and the p value is = 0.02575, indicating a significant correlation. Negative correlation, in this case, means that MNI inaccuracy increases as the body to body parts ratio decreases. It is worth noting that Fig. 2 Non-Linear function of B/BP ratio and MNI inaccuracy. Nonðx−xc Þ2 w2 A ffi −2 linear equation: y ¼ y0 þ p e π w 2 Fig. 3 Exponential function of B/BP ratio and MNI inaccuracy. Exponential equation: y ¼ y0 þ AeR0 x Spearman’s rank correlation, which is also able to be used in this case, gives even more impressive results with a p value = 0.01667. Three types of relationships between the variables were tested; linear, non-linear and exponential function (Figs. 1, 2 and 3). Discussion Although a linear equation is the simplest to interpret it does not describe accurately the relationship between B/BP ratio and MNI error. The extrapolated line of linear correlation in Fig. 1 intersects the B/BP ratio axis at around 1.35 at the same time indicating 0% of MNI error on the other axis. This is not an accurate prediction because the calculation for the highest dot on the graph (Snagovo 04) shows a higher ratio (1.438) at 54% of MNI error. At the other end, the line of correlation intersects the MNI error axis around 440%, which is less than 513% (Cancari Road 06), also indicating a low prediction accuracy. As shown in Fig. 2, a non-linear relationship describes the low end distribution of the B/BP ratio accurately where MNI errors are highest. The line of correlation passes through the highest MNI error (513% for Cancari Road 06) point but does not intersect the horizontal axis afterwards. Rather, the line flattens and becomes parallel to the MNI error axis, leaving space for extrapolations even within lower ratios and higher errors than used in this data set. On the other end, where the ratios are the highest and the errors lowest, the extrapolated line of correlation seems to be even less accurate than with a linear fit, achieving 0% error at a ratio around 1.2 B/BP. Figure 3 shows that an exponential equation dose not describe accurately the low end of the distribution. The line of correlation intersects the horizontal axis at 475% (somewhat Author's personal copy Forensic Sci Med Pathol better than linear function) which is less than the highest 513% from the data set. On the other hand, with further extrapolation, the line of correlation would intersect the vertical axis at value of 2 showing 0% of error on the other axis. A value of 2 on the B/BP axis would correspond, for example, with 100 complete bodies and 50 body parts found in the grave and according to the exponential function of this data set that is a threshold for accurate MNI assessment. Any value below 2 can count with particular error in estimation. In situations where values of B/BP are large an exponential equation works best and when they are small a non-linear relationship has a better fit. To describe both ends of the spectrum with single equation, the data set needs to include a larger input with less comingled samples. This is important for prediction of MNI error because if function is not adequate prediction will not be accurate. In general, the results of the study indicate that the complexity of a mass grave has significant effects on the accuracy of the minimum number of individuals estimation. Ideally, one case number represents one individual. This is a common occurrence within primary burials but with secondary burial sites, one case number might represent just a small body part, e.g. right foot or left ulna and radius. These secondary sites also generate a large number of unassociated single bones that cannot be designated as body parts because of their lack of articulation so they are usually recorded as general body parts. Complexity rises considerably with tertiary mass graves or multiple deposit interment sites [14]. The majority of individuals in the secondary mass graves considered in this study are represented with just a body part or even with a single bone while the remaining body parts are scattered in different mass grave locations. These disarticulated cases, which are often the only evidence of a person in particular grave, prove elusive for MNI because they are typically not represented with long bones, which are most frequently used in MNI estimation (Fig. 4). Generally, there are several problems with establishing accurate MNI in comingled mass graves. Often, the basic problem is a lack of a proper archaeological methodology involved in the excavation of mass graves. Application of a strict stratigraphic, unit-based methodology, among other things, strongly reduces the level of body disarticulation during recovery [21]. It has been shown from two Batajnica mass grave sites that the stratigraphic excavation method compared to the so-called pedestal method gives better results [23]. Optimal results are obtained via a combination of the spatial analysis of mass grave mapping data, and the stratigraphic approach to the excavations [24]. The disparity that can occur in calculating numbers of individuals using osteological methods of assessment could be substantial [13]. Also, the use of different techniques can produce disparities in estimation [25], but in essence, MNI estimation validity depends on the percentage of the individuals represented by the excavated body elements [26–28]. Fig. 4 Commingled bones from Cancari Road 10 The results of the present study demonstrate that a body to body parts ratio (B/BP + GBP) when compared to MNI inaccuracy shows a significant correlation i.e. the smallest body to body parts ratio correlates to the largest MNI inaccuracy, meaning that more disarticulated bones in relation to complete bodies (more complex site) means larger inaccuracy in MNI estimation. This is logical but needed quantification to numerically determine what proportion of disarticulated elements compared to complete bodies gives a particular level of inaccuracy so that we could use this correction in complex sites in the future and increase the MNI estimation accuracy. All the sites used in this paper for analysis are of the same type (secondary ramp mass graves) and were excavated/ analyzed by the same crew in similar conditions, limiting the number of variables that may have an impact on our research. Nevertheless, the study is limited by the relatively small sample and could be expanded with more comingled sites from different contexts in order to improve the accuracy of the presented method. With more samples calculated from less comingled sites and from primary sites it would be possible to safely interpolate both ends of the data with single function. Currently, a non-linear function is better with low values of B/BP and an exponential function works well with higher B/BP ratio values. The function predicts what the inaccuracy of the MNI would be for different values of the B/BP index. So, based on data from the B/BP ratio calculation, a researcher could calibrate MNI accordingly and improve the estimation. Calculating the ratio of body parts to bodies could also be useful for the excavation process itself. If, during excavation, the index value indicates that a mass grave is complex, subsequent excavation should proceed slowly and carefully, with as many items as possible recorded “in-situ” and perhaps more importantly, the collection of samples for DNA based identifications should be expanded even to general body parts. Author's personal copy Forensic Sci Med Pathol Key points 1. We investigated the MNI accuracy of five secondary mass graves using anthropological data and DNA identifications. 2. A body to body part ratio was introduced to assist in quantifying the complexity of the mass grave. 3. Quantification of the complexity of a mass grave allows determination of how the complexity influences the accuracy of MNI. 4. There was a significant correlation between the body to body parts ratio and the MNI (in)accuracy. 5. This correlation could be used to improve the accuracy of MNI and thus improve the methodology of excavations. 9. 10. 11. 12. 13. 14. Acknowledgements This study was supported by ministry of science of republic of Serbia, grant no. 45005. Compliance with ethical standards 15. 16. Conflict of interest There are no conflicts of interest. Human participants and/or animals Living human participants and/or animals were not subjects of the conducted research. 17. Informed consent Informed consent was not applicable to this study, only osteological material involved. References 1. 2. 3. 4. 5. 6. 7. 8. Stock C. A census of the Pleistocene mammals of Rando La Brea, based on the collections of the Los Angeles Museum. J Mammal. 1929;10:281–9. Howard H. A census of the Pleistocene birds of Rancho La Brea from the collections of the Los Angeles Museum. Condor. 1930;32: 255–71. White TE. A method of calculating the dietary percentage of various food animals utilized by aboriginal peoples. Am Antiq. 1953;4: 396–8. Adams BJ, Konigsberg LW. Estimation of the most likely number of individuals from commingled human skeletal remains. Am J Phys Anthropol. 2004;125:138–51. Adams BJ, Konigsberg LW. How many people? Determining the number of individuals represented by commingled human remains. In: Adams BJ, editor. Recovery, analysis, and identification of commingled human remains. Totowa: Humana Press; 2008. p. 241–55. Byrd JE, Adams BJ. Osteometric sorting of commingled human remains. J Forensic Sci. 2003;48:717–24. Ubelaker DH. Approaches to the study of commingling in human skeletal biology. In: Haglund WD, editor. Advances in forensic taphonomy: method, theory, and archaeological perspectives. Boca Raton: CRC Press; 2002. p. 355–78. Konigsberg LW, Adams BJ. Estimating the number of individuals represented by commingled human remains: a critical evaluation of methods. In: Adams BJ, editor. Commingled human remains. Methods in recovery, analysis, and identification. Oxford: Academic Press; 2014. p. 193–220. 18. 19. 20. 21. 22. Byrd JE, Adams BJ. Analysis of commingled human remains. In: Ubelaker DH, editor. Handbook of forensic anthropology and archaeology. 2nd ed. New York: Routledge; 2016. p. 226–42. Burns K. The forensic anthropology training manual. 3rd ed. Boston: Pearson Education; 2012. p. 196–7. Kontanis EJ, Sledzik PS. Resolving commingling issues during the medicolegal investigation of mass fatality incidents. In: Adams BJ, editor. Recovery, analysis, and identification of commingled human remains. Totowa: Humana Press; 2008. p. 317–36. Nikita E, Lahr MM. Simple algorithms for the estimation of the initial number of individuals in commingled skeletal remains. Am J Phys Anthropol. 2011;146:629–36. Lambacher N, Gerdau-Radonic K, Bonthorne E, Valle De Tarazaga Montero FJ. Evaluating three methods to estimate the number of individuals from a commingled context. J Archaeol Sci Rep. 2016;10:674–83. Jessee E, Skinner M. A typology of mass grave and mass graverelated sites. Forensic Sci Int. 2005;152:55–9. Haglund WD, Reay DT, Swindler DR. Tooth mark artifacts and survival of bones in animal scavenged human skeletons. J Forensic Sci. 1988;33:985–97. Ubelaker DH. Taphonomic application in forensic anthropology. In: Haglund WD, Sorg MH, editors. Forensic taphonomy: the postmortem fate of human remains. Boca Raton: CRC Press; 1997. p. 77–90. ICTY report presented to the International Criminal Tribunal for the former Yugoslavia: The 2009 integrated report on Srebrenica missing including а progress report on DNA-based identification by Helge Brunborg, Ewa Tabeau and Arve Hetland. https://www. google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1& ved=2ahUKEwiplO6fnuvkAhWOILcAHQA9BnAQFjAAeg QIAhAC&url=https%3A%2F%2Fsrebrenica.sense-agency.com% 2Fassets%2Flasting-consequences%2Fsg-7-01-ekspertski-en. pdf&usg=AOvVaw0U4HjoVOBLiIiuFtsKFtlR. Accessed 21 June 2019. Yazedjian L, Kešetović R. The application of traditional anthropological methods in a DNA-led identification process. In: Adams BJ, Byrd JE, editors. Recovery, analysis, and identification of commingled human remains. Totowa: Humana Press; 2008. p. 271–84. Djuric M. Dealing with human remains from recent conflict: mass grave excavation and human identification in sensitive political context. In: Blau S, Ubelaker DH, editors. Handbook of forensic anthropology and archaeology. 2nd ed. New York: Routledge; 2016. p. 532–45. ICTY report presented to the International Criminal Tribunal for the former Yugoslavia: Update to the summary of forensic evidence exhumation of the graves and surface remains recoveries related to Srebrenica - June 2013 by Dusan Janc. https://www.google. com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&ved= 2ahUKEwj2oqL1nuvkAhVf7HMBHUENCvMQFjAFegQIBxAC &url=https%3A%2F%2Fsrebrenica.sense-agency.com% 2Fassets%2Fexhumations%2Fsg-2-08-summary-eng.pdf&usg= AOvVaw2i_yNyS1QP6Hk1jP-138-e. Accessed 16 June 2019. Tuller H. Mass graves and human rights: latest developments, methods, and lessons learned. In: Dirkmaat D, editor. A companion to forensic anthropology. Malden: Wiley-Blackwell; 2012. p. 157–74. Reports from ICMP identification process. https://oic.icmp.int/ index.php?w=site_summary&l=en&x=search&xw= siteSummaryFilterLoadSitesSitecode&x_region_id_sel=&x_ municipality_id_sel=&x_municipality_place_id_sel=&x_site_id_ sel=&x_sites_sitecode_id_sel=&quick_find_pp=15&quick_find_ q=&country_id=33&region_id=6&municipality_id= 3342&municipality_place_id=228&site_id=3214&sites_sitecode_ id=1614. Accessed 20 June 2019. Author's personal copy Forensic Sci Med Pathol 23. 24. 25. Tuller H, Đurić M. Keeping the pieces together. Comparison of mass grave excavation methodology. Forensic Sci Int. 2006;156: 192–200. Tuller H, Hofmeister U, Daley S. Spatial analysis of mass grave mapping data to assist in the reassociation of disarticulated and commingled human remains. In: Adams BJ, Byrd JE, editors. Recovery, analysis, and identification of commingled human remains. 1st ed. Totowa: Humana Press; 2008. p. 7–29. Herrmann NP, Devlin JB, Stanton JC. Assessment of commingled human remains using a GIS-based and osteological landmark approach. In: Adams BJ, Byrd JE, editors. Commingled human remains. Methods in recovery, analysis, and identification. Oxford: Academic Press; 2014. p. 221–37. 26. Casteel RW. Characterization of faunal assemblages and the minimum number of individuals determined from paired elements: continuing problems in archaeology. J Archaeol Sci. 1977;4:125–34. 27. Grayson DK. Minimum numbers and sample size in vertebrate faunal analysis. Am Antiq. 1978;43:53–65. 28. Turner A. Minimum numbers estimation offers minimal insight in faunal analysis. OSSA. 1980;7:199–201. Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.