HKP Work Camp

Abstract
Major Karl Plague was a German officer during World War Two responsible for saving 250 Jewish forced labor workers at HKP 562 in Vilnius, Lithuania. The 750 other workers were captured and killed by Nazi SS members on their retreat out of the country during Adolf Hitler’s “Final Solution”, their bodies buried in an unmarked grave. In the summer of 2017, an international team of Jewish scholars, archaeologists and geophysicists were invited to HKP to investigate possible locations of a mass grave, execution trench and entrance to a hiding place for Jewish survivors of the camp. To investigate these locations ground penetrating radar (GPR) and electrical resistivity tomography were used. Using 225 and 450 MHz antennae with a step size of 0.1m and 0.05m (respectively), GPR data was collected over 5 grids, varying in size. Grids were located over a monument where the mass grave is suspected to be located, along the back wall of one of the buildings searching for the execution trench, and in the basement of the same building looking for the hiding place of some of the Jewish survivors. Results showed extensive stratigraphic dipping along the back side of the building along with an anomaly in the basement believed to be the entrance to a hiding place.

Introduction

On June 22, 1941 Nazi Germany initiated Operation Barbarossa, the invasion of eastern Europe, as part of the regime’s goals to expand their empire eastward. This was due to the Nazi idea of creating more living space for their perceived master race, the Aryans. This idea of eastern expansion was termed “Lebensraum” or in English, living space (Carter, 2018). The policy’s intention was to colonize much of eastern Europe so that the Aryan Race could flourish in the agriculturally rich areas such as Poland and Ukraine. In order to do this, they needed to “rid” the area of its local non-Aryan inhabitants (Kamenetsky, 1961). One of the groups that the Nazis had a deeply held hatred for was the Jews. The Nazi Regime blamed the Jews for the loss of the First World War and the economic depression that followed the Treaty of Versailles. The Nazis exploited this propaganda and used it effectively in their rise to power. Jews were continually subject to laws that prohibited their rights and eventually lost German citizenship (Tschentscher, 2010).  

Prior to Operation Barbarossa, Molotov-Ribbentrop Treaty (1939) was signed. The treaty effectively split Poland in half between Nazi west and Soviet east, as many as 300,000 Jews fled from Nazi occupied Poland into Soviet occupied territory, including Lithuania. This greatly increased the Jewish populations in Eastern Europe (Vilna During the Holocaust). 


When the Nazis invaded the Lithuanian city of Vilnius on June 22, 1941, as part of Operation Barbarossa, they immediately began rounding up the local Jewish population (Figure 1). This was done with the aid of local collaborators who gave information to the whereabouts of Jews as well as arresting Jews themselves. Much of the Lithuanian cooperation was a result of the Jews being accused of being communists and supporting the Soviets who had invaded the country just two years earlier following the Molotov-Ribbentrop Treaty (Vilna During the Holocaust).  Under soviet occupation, private business was abolished and became state owned. This led to much economic strife within the country and many business owners resented this. Using this to their advantage, the Nazis used this hardship as a means of propaganda to insight young nationalistic Lithuanian men into helping them in their goals of ridding eastern Europe of its Jewish population. With the aid of their Lithuanian supporters, many Jews where in Vilnius were arrested and murdered (figure. 2). The rest of the Jews were forced into a small corners of the city center that became the Vilnius Ghettos (figure 3 and 4). Shortly after the creation of the ghettos, the ghettos were liquidated by their Nazi occupiers through a series actions (Vilna During the Holocaust). Those unfortunate enough to be chose as part of the liquation were brought to the near by forest of Ponar by train and executed (Goode, 2009). By the end of the war as more than 75,000 people were murdered at Ponar (Vilna During the Holocaust).

Figure 1. Location of Vilnius Lithuania where the HKP work camp is located.

Figure 2. A group of Jews who were murdered in Vilnius shortly after the Nazi occupation of the city (Vilna During the Holocaust).

Figure 3. Map displaying the location of the ghettos in  Vilnius, Lithuania (Webb, and Lisciotto, 2006).

Figure 4. Photo of one of the ghetto's gates (Webb, and Lisciotto, 2006).

Many of the residents of the ghetto were working aged men and women who the Nazi’s felt could serve a purpose to help the Wehrmacht (German Army) succeed. Thus, forced labor camps were created throughout the city (Goode, 2009). One of these camps was Heereskraftfahrpark (HKP) 562 (Figure 6). The camp served as a repair shop for damaged Nazi vehicles and was run by Major Karl Plagge (Figure 7 and 8) (Goode, 2009). Though a Nazi himself, Plagge was astounded at the capacity for violence towards the Jewish civilians the Nazi’s had. He worked hard to ensure that 1,000 of the Jews from the ghetto were given “essential worker” cards and housed within the camp. Not only did this keep them from the violence that occurred on a day to day basis within the ghetto, but it also ensured the Jews would be safe when the ghetto was liquidated (Goode, 2009). However, in 1944, it became clear that Germany was losing the war. During their retreat from Lithuania from the encroachment of the Red Army, the SS were ordered to liquidate any and all camps they came upon. Just before leaving the camp, Major Plagge secretly let the 1,000 Jews of his camp know that the SS would be entering the camp soon to take them to nearby killing locations. 500 of the HKP Jews hid in hiding places throughout the camp called “malines”. The other 500 Jews who were not in hiding were taken away to the killing pits of Ponar. With 500 prisoners being unaccounted for, the SS knew that there had to be more people within the camp. After an extensive search, 250 of the HKP Jews in hiding were found and killed in the camp courtyard; their bodies buried in a shallow grave on the back side of the camps west building, Apartment 2 (Figure 9). The final 250 Jews that were not found remained in hiding until the Red Army came into the city and they knew they were safe to leave their hiding spots. Many of the Jews who survived were forced to remove some of the bodies from the shallow grave in order to bury them in a deeper location. Nearby, directly in between the two camp buildings, there had been a deep pit dug to park the vehicles. Many of the bodies were moved from the shallow grave to this location and buried. Today, a commemorative monument is in place over the location of the mass grave. In the summer of 2017, an international team of Jewish Scholars, Archaeologists and Geophysicists were brought to the site in order to 1) locate the entrance to one of the hiding places in Apartment 2’s basement, 2) confirm that there had been a mass grave dug on the back side of the west building, and 3) confirm the existence of a mass grave beneath the monument in the courtyard.

Figure 5. A photo of the HKP work camp (Lisciotto).

Figure 6. Photo of Karl Plagge in his Nazi Uniform (Lisciotto, 2010).

Figure 7. Photo of the HKP workshops. These are the workshops in which the Jews imprisoned at the HKP repaired Nazi vehicle (Webb, and Lisciotto, 2006).

Figure 8. Map of the current state of the former HKP work camp. The map was created using a UAS photograph created by Paul Bauman in 2017.

Methods
In the summer of 2017, a ground penetrating radar (GPR) survey and ERT lines were collected at the assumed location of a mass grave, burial trench and meline entrance at the HKP site in Vilnius, Lithuania. The purpose of the project was to verify the existence of each of the three features and their dimensions. GPR is a non-invasive technology that emits electromagnetic energy into the subsurface. The energy reflects off of subsurface objects and stratigraphy due to varying dielectric properties of the materials. Data was collected using pulseEKKO 1000 GPR system with 225 MHz and 450 MHz antenna with a step size of 0.1 m and 0.05 m respectively. A total of five grids were collect along with two electrical resistivity tomography (ERT) lines. Three grids (1,2,3) were collected on the back-side apartment 2 looking the execution trenches. Grids 4 (225 MHz) and 5 (450 MHz) were collected in the courtyard between the apartment buildings searching for the mass grave. Two sets of three parallel transects were also collected in the basement of the west building where the entrance to the meline was believed to be located using both 225 MHz and 450 MHz antenna. The locations were selected based upon eye-witness accounts. Topographic data of the grids were all collected using a Topcon laser leveling system. Grid lines were collated in GFP Edit to arrange them in the specific order in which they were collected. All data was then imported into EKKO_Project processing software that organized the lines to view reflections below the surface. In addition to the GPR survey, there we two electrical resistivity tomography (ERT) lines collected at the HKP site. The first ERT line was collected along the backside of Apartment 2 and through Grids 1, 2 and 3 to a length of 50 meters. The second ERT line was collected diagonally through Grids 4 and 5. The ERT results were processed by Alistar McClymont and Paul Bauman of Advisian WorleyParsons.

Figure 9. A diagram created in Adobe Illustrator showing the location of three GPR Grid collected east of Apartment 2. Within each of the grids, the direction and orientation of each GPR line collected can be seen. Across the three GPR grids the location of the ERT line can also be seen.

Figure 10. A drawing by Gary Gerstien who hid in the meline and survived the war. This drawing along with the direction of his family members helped determine where the GPR survey was to be collected in the basement of Apartment 2.

Figure 11. Map of the GPR survey collected at the HKP work site in the summer of 2017.

Results
When analyzing the results from Grid 1, the reflections in the subsurface appear to be discontinuous and nonuniform throughout the grid (Figure 13). The GPR profiles within the are attenuating at roughly 2 meters into the subsurface. When viewing the results from ERT 1, the ERT profile has a circular area of low resistivity in the area where the GPR grid was collected and where the signal attenuates (Figure 16). This area of low resistivity is likely the result of the area storing relatively more water than the surrounding area making it more conductive to electrical energy.

Figure 12. Example of a horizontal GPR profile in Grid 1. Below 2.4 meters the signal becomes attenuated. The attenuation of the GPR signal corresponds to the area of low resistivity in the ERT profile collected over the same location (Figure. 15).

When analyzing Grid 2’s horizontal profiles, in an area near the apartment there are areas that have inclined reflectors in the form of a truncation (Figure 14). The truncation has ununiform stratigraphy above (Figure 14). It is also important to note that area allows for deeper GPR penetrating, highlighting the fact the area has a different soil structure/composition than the areas found outside the truncation. When viewing the SliceView images of Grid 2, this anomalous area is also highlighted by areas of higher amplitude.  This anomalous area also matches the area in which the ERT 1 line found a circular anomaly (Figure 15).

Figure 13. GPR profile collected in Grid 2 located at 3 meters along the x-axis. The profile shows a dipping GPR reflector (highlighted by the red line) that extends from 0.8 to 2.8 meters in depth. Above this reflector there is an area of nonuniform stratigraphy that may be the result of a previously excavated area.

Figure 14. SliceView image at a depth of 1.33 to 1.44 meters that shows the area of nonuniform stratigraphy found in the horizontal GPR profile shown above (Figure. 13) highlighted by the red rectangle. This area shows higher amplitude readings than the surrounding area. Again, this area is also highlighted as an area of low resistivity in the ERT profile collected through the GPR grid (Figure. 16)

Figure 15. The processed ERT results from the ERT line that runs through the GPR grids on the west side of Apartment 2. The circular area of low resistivity (A) corresponds to the anntenuated area in Grid 1. The circular area of low resistance (B) corresponds to the area of nonuniform stratigraphy found in the horizontal GPR profile in Grid 2 and the highlighted area of higher amplitude in the SliceView image of Grid 2 (Figure 14).

Grid 3 showed similar results to Grid 2. There is, again, an inclined reflection in the form of a truncation. The stratigraphy of this line is not as uniform than the results from grid and shows more hyperbolic reflections.

Figure 16. Horizontal GPR profile from Grid 3 located at the 11 meter mark along the x-axis. In this profile there is an inclined reflector that is similar to the profile in Grid 2 (Figure 13).

Figure 17. SliceView image of Grid 3 at 0.778 to 0.889 that shows a rectangular area of relatively higher amplitude than the surrounding area. this area corresponds to the above the inclined reflector found in the GPR profile (Figure 16).

Grid 4 contained mostly non uniform reflection patterns throughout the grid. At the bottom of the profile at 3.5 meters in depth, near where the signal attenuates, there is a linear feature that is dipping at a slight angle. This linear feature matches the results of the more electrical resistive material found in the ERT results from ERT 2 (Figure 20). The ERT results above this layer there is a circular area of relatively low resistance. This would also account for the area being less resistive to electrical energy from the ERT as the area may be less compact and therefore holding less water, making it less resistive. 

Figure 18. Horizontal GPR profile collected at the 21 meter marking mark going through the center of Grid 4. At a depth of 2.3 to 3.5 meters and depth a linear reflector can be seen. This linear reflector corresponds to the bottom of the area of higher resistivity in the Figure 19. The stratigraphy above this reflector contains hyperbolic features as well as downlapping stratigraphy onto this layer. 

Figure 19. The processed ERT profile from ERT 2. This ERT profile was collected diagonally through Grid 4. The orange area below the highlighted circular area of low reflectance is showmn in the previous GPR profile (Figure 18). The circular area runs the length of the monument area, roughly 16 meters.

Being that Grid 5 was collected with 450 MHz antenna there was less depth penetration than in the previous four GPR grids. With the shallower depth of penetration, the linear feature seen in Grid 4 was not detected as the depth of the profile reached a depth of 2.4 meters.

Figure 20. A horizontal GPR profile collected  at the 7 meter mark along the x-axis in Grid 5. Within this profile there can be seen more hyperbolic features and discontinuous linear features. 

Analyzing the two sets of transects collected in the basement of Apartment 2 there is a truncation in the profiles at 3.75 meter position. This truncation corresponds to the location suggested in the map of the basement created by the survivors.

Figure 21. A horizontal 225 MHz GPR profile collected in the basement of Apartment 2. From 3.55 to 3.85 meters along the profile there is a truncation (highlighted in red).

Figure 22. A horizontal 450 MHz GPR profile collected in the same location as the 225 MHz GPR profile above (Figure 21). The 450 MHz antenna allows for more detail to be shown than the 225 MHz antenna. The truncation is present throughout the depth of the profile (highlighted in red).

Discussion
The processed GPR results from Grid 1. There does not seem to be much evidence of a potential burial trench or mass grave. The nonuniform and chaotic nature of the stratigraphy may suggest that the area has been anthropogenically disturbed. The attenuation of the GPR signal at 2 meters in depth matches the area of low resistivity is in the same location. This may be the result of the soil below 2 meters having relatively higher amounts of stored water, which would lead to the signal being attenuated (Jol and Bristow, 2002). Given this information, this may be the result of a potential burial pit/mass grave that was dugout and then filled, giving the area different characteristics than the surrounding area.
Results from Grids 2 and 3, show inclined reflections that may have been the result of digging (Shultz, 2008, Conyers, 2006). The stratigraphic layers above the truncation in Grid 2 may also be the result of anthropogenic activity, given their chaotic nature. This may be the result of the area being dug up and later refilled. The area with the truncation and the stratigraphy above are, again, in the same location in which a circular anomaly of low resistivity can be seen in ERT 1. Grid 3 also shows a similar truncational feature. The hyperbolic features may indication the remains of deceased people (Schultz, 2008). Combining this geophysical evidence and the existence of bullet holes on the adjacent wall of the building, it is plausible that this may be the location of the execution trench or mass burial.
The GPR results from Grid 4 highlight the area an inclined reflector that is at the bottom of the circular anomaly found in ERT 2. The stratigraphy above, highlighted in Grid 5, shows many hyperbolic features found in the subsurface above the inclined reflector. These may have been caused by the presence of human remains (Shultz, 2008). The circular area of low reflectance may be an area that stores more water as a result of being dug up and filled in. Areas of known graves have also been shown as places with lower resistivity due to water rich ions from decomposing bodies (Nero, et al. 2016).
The GPR lines collected in the basement of Apartment show evidence of a anthropogenic truncation (Conyers, 2006). This truncation is in the location that a survivor’s drawing and his family members had suggested. This provides evidence that the truncation might, in fact, be the location of a maline entrance when the camp was being liquidated by the SS.

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