The issue of errors in external post-mortem examinations, extending to missed homicides, is exceedingly complex [3, 4, 26, 27]. Several aspects can classify the causes of these errors: inherent limitations of the external examination itself, structural factors such as legal regulations, situational factors like family expectations for a natural death determination or challenging conditions such as decomposition, police biases favoring natural death cases, and medical reasons [5, 26]. These medical errors encompass a broad range, from incomplete examinations without inspection of body orifices to overlooking subtle or evident signs of external violence, careless identification of the body, misjudgments regarding the time of death, cause of death, manner of death, and the incorrect formation and classification of causal chains. [2, 5, 26, 28]. From the perspective of forensic medicine, an important contribution to reducing this issue can be made by providing more intensive and practice-oriented training for medical students, as well as continuing education for doctors obliged to conduct external post-mortem examinations. In recent years, several concepts for corresponding teaching, learning, and examination methods have been introduced, but they have not yet become widespread. Schmeling et al. [10] described a web-based e-learning program in the form of a "Click and Point Adventure" for training in external post-mortem examination, which also takes into account the environment of the corpse. Ebert et al. [29], replicated a crime scene by reconstructing it in virtual reality, while Koller et al. [30] used the VR environment for the specific tasks of external forensic examination and measurement of injuries. Another analog variation is the already described training with simulation mannequins and the additional participation of actors as simulation patients [20], which also represents a comprehensive setting for corpse inspection. In all mentioned scenarios, practical training for external post-mortem examination is emphasized, and the teaching of how to fill out a death certificate is omitted. Also current practical exams reflect this strategy, where the actual performance of the external post-mortem examination and the filling out of the death certificate are separated. Especially during exams, such as OSCE exams (Objective Structured Clinical Examination), the tight time schedules are apparent which lead to considering the corpse environment only marginally [18]. This assessment is likely to apply equally to the integration of this topic into OSPE formats (Objective Structured Practical Examination) [11, 12].

In order to largely cover the spectrum of potential medical sources of error, both the practical external post-mortem examination with consideration of the environment and the completion of the death certificate in a case scenario are intertwined in the virtual external post-mortem examination [22]. Throughout the first evaluation phase at the Halle site, the differences and potential advantages over previous projects were demonstrated. In the current study, alongside an updated inventory of similar projects and a comparison to these applications, the main focus was to examine to what extent such a learning concept can also be successfully disseminated across different locations. Likewise, the limitations and boundaries of the method must also be critically discussed.

Before the virtual external post-mortem examination, almost all students had attended the lecture on thanatology, and over two-thirds had completed the external post-mortem examination practicum. As a result of these courses, students generally assessed their own skills and competencies in conducting practical external post-mortem examinations and filling out death certificates rather conservatively, as it had been observed previously at the Halle site [22]. This assessment supports the need to establish additional teaching and learning methods for the medical external post-mortem examination that goes beyond the current, still widely used concept of lectures and practicums [15].

Unlike the approach at Halle, an e-learning module was introduced in Dresden as a preparatory tool for the virtual external post-mortem examination and included additional items in the evaluation. Both the self-study unit for preparation and the materials provided were met with a high proportion of favorable evaluations. These results suggest that the modification of the onboarding phase implemented in Dresden should also be adopted in Halle and possibly at other locations. At this point, the modular usability of the virtual reality application also becomes apparent. Acting as a practical component within forensic medicine educational offerings, it was able to supplement dissemination of knowledge by a tutor (Halle) as well as an e-learning programme (Dresden). Additional fields of application are conceivable and should be investigated.

The duration of one hour deemed appropriate by nearly two-thirds of the students, and the group size of four participants, which was rated as optimal by all attendees, suggest that the time frame of at least one hour and the small group format should be maintained in the future. This is especially pertinent since teaching units conducted in small groups are associated with higher learning success compared to larger group formats [31, 32]. Simultaneously, considering the preferences of students who favor a longer format and the evaluation results of the pilot study [22], it would be advisable to extend the course offering to two hours, provided the time frame allows it.

Both the technical and the subject-specific support provided by the tutors was rated as exceptionally helpful, yet there was still ample space left for encouraging independent thinking. This balance was also positively highlighted by the students in their open-ended feedback, referring to it as a "pleasant, educational atmosphere." During the course, the support from the tutors, including the possibility of intervention, seems justified given that for most participants, handling virtual reality was largely unfamiliar. In fact, three quarter of students stated no or little experience with VR applications in Dresden which was a consistently high rate and similar to the initial assessment in Halle, four years earlier [22].

Correspondingly, the assessment of the practical operation of the VR format was balanced between easy and difficult handling. According to Speidel et al. [33], student reservations are due to a lack of experience with VR technology, and its significance for current and future teaching is viewed with some skepticism. Although it is expected that such concerns will decrease as digitalization in the work and leisure environment continues to grow, especially accelerated by the COVID-19 pandemic, this challenge must still be adequately considered when further establishing VR technology in medical education, along with the well-known issue of "motion sickness." In Dresden, this aspect was included as an additional item in the evaluation, with over 40% of participants indicating that they had faced this phenomenon at least occasionally during previous VR usage. As motion sickness is a known issue with VR applications in other fields, a workaround was implemented through task distribution in small groups. This allowed students to follow activities by "looking over the shoulder," eliminating the need to wear VR goggles for the entire duration of the course.

In the 2020 study in Halle, the technical implementation and realism of the simulated external post-mortem examination using VR technology were rated as fully or predominantly positive by almost two-thirds of the participants. In the meantime, the application has been further developed and optimized. However, the realism was rated positively by only 53.3% of the participants in Dresden, whereas the technical implementation of the virtual external post-mortem examination was rated as fully or predominantly positive by 91.8%. Since primarily modifications have been made to the interaction concept and the spatial design has remained largely unchanged, an increased demand for aesthetics in virtual environments can be inferred, which may have arisen due to advancements and expectations from the gaming industry. To continuously ensure a realistic representation, it is necessary to optimize the environment according to current standards, now, that this increased expectation has been detected.

Regarding the content and learning objectives of the VR training, the evaluation results showed that, at least according to the participants' assessments, forensic skills and abilities could be significantly enhanced. Over 90% of the participants felt much more confident in conducting a practical external post-mortem examination as well as filling out a death certificate after the course. These approval rates were significantly higher than in the previous study in Halle [22], where the acceptance rate for the practical external post-mortem examination was at 52.5% and for filling out the death certificate was at 62.5%. Whether these differences can be solely attributed to the modified concept in Dresden with an online preparation unit and the technical optimization of the VR application is questionable and should be examined in more detail. In the same way the extent of the actual long-term learning success should be assessed in a corresponding examination format. Furthermore, the course should also be evaluated in a larger cohort than in the limited number of participants in the present pilot event.

In the overall assessment, nearly all participants (98.4%) deemed the repetition of forensic medical content as meaningful, and the virtual external post-mortem examination was predominantly positive (87.1%) considered a suitable didactic tool for this purpose. These approval rates were even slightly higher than those in the Halle study [22], which showed 85.0% for meaningful repetition of content and 64.1% for the suitability of the virtual external post-mortem examination as a didactic instrument. Moreover the highly positive reception of the newly introduced learning concept among students in Dresden was reflected in the overall grades and the rate of recommendation. Other studies have also attributed high didactic potential to VR technology due to its more sustainable learning effects compared to other digital and traditional teaching methods [33, 34].

In the applications in Dresden and Halle, it was determined that the simulated external post-mortem examination using VR technology offers advantages over the real post-mortem examination. These include higher standardization and reproducibility of findings, as well as the effectiveness and independence from spatial, temporal and situational resources [22]. Based on these advantages, the use of VR technology as a testing method is recommended, especially since simulation mannequins have already been successfully used in the practical examination of external post-mortem examination [18, 19]. Whereas, in accordance with Speidel et al. [33], the reliable establishment of teaching formats using VR technology is a prerequisite.

However, in terms of sensory feedback, the simulated external post-mortem examination using VR technology has multiple inherent weaknesses, which comprise the absence of tactile and olfactory sensory impressions and the consequent lack of need to overcome emotional barriers [22], which are important causes of errors in real external post-mortem examinations [26]. Based on these experiences from the 2020 evaluation, the issue was addressed in Dresden as well, confirming that for over 90% of the students, training on a real corpse remains indispensable despite the learning effect of the virtual external post-mortem examination. Therefore, to achieve medium and long-term improvement in the quality of medical post-mortem examinations, pursuing intensified practical training is recommended, involving a combination of training on both real and virtually simulated corpses.