Consideraciones médico-legales laborales de la fórmula de Balthazard / Occupational medical-legal considerations of the Balthazard formula

La determinación del porcentaje de pérdida en pacientes lesionados con múltiples secuelas por riesgos de trabajo resulta un verdadero reto para el perito, esto adquiere mayor relevancia cuando en el fuero judicial se pueden presentar discrepancias en los criterios para el uso o no de fórmulas matemáticas para el cálculo. La fórmula de suma combinada, creada por el Médico Forense Víctor Balthazard, no es más que un ordenamiento de una regla de tres que ordena los porcentajes otorgados a cada secuela de mayor a menor para evitar que el porcentaje final sobrepase el 100%, o bien que resulte en un porcentaje mayor que una secuela única puntuada en el baremo y que por gravedad en la intensidad de la misma resulte con un porcentaje menor al calculado por la secuela múltiple y que se ha utilizado en fueros laborales y de seguridad social alrededor del mundo. El Baremo contenido en el Código de Trabajo no establece explícitamente la forma en que se calcula el porcentaje de pérdida por secuelas múltiples, lo cual brinda libertad al perito para utilizar fórmulas, como lo es la fórmula de suma combinada, que permite calcular de forma congruente las pérdidas sucesivas sin sobrepasar a la persona más allá de su capacidad general total del 100% o de otorgar porcentajes mayores a secuelas de mayor gravedad que la suma de las pérdidas por el evento que se está valorando.

The determination of the percentage of loss in injured patients with multiple sequelae due to occupational hazards is a real challenge for the expert, this becomes even more relevant when in the judicial system there may be discrepancies in the criteria for the use or not of mathematical formulas for the calculation. The combined sum formula, created by the Forensic Physician Victor Balthazard, is nothing more than an arrangement of a rule of three that orders the percentages given to each sequel from highest to lowest to avoid that the final percentage exceeds 100%, or that it results in a higher percentage than a single sequel scored in the scale and that due to the severity in the intensity of the same results in a lower percentage than that calculated for the multiple sequel and that has been used in labor and social security courts around the world. The Schedule contained in the Labor Code does not explicitly establish the way in which the percentage of loss for multiple sequelae is calculated, which gives the expert the freedom to use formulas, such as the combined sum formula, which allows a congruent calculation of the successive losses without exceeding the person's total general capacity of 100% or to grant higher percentages to sequelae of greater severity than the sum of the losses for the event being valued.

Macroscopic assessment of environmental trace evidence dynamics in forensic settings.

Environmental trace evidence offers useful circumstantial intelligence to link persons and scenes of forensic interest. An increasing empirical research base is dedicated towards understanding the transfer and persistence dynamics of environmental indicators including pollen, soils, and diatoms, within a diverse range of experimental frameworks. This paper presents two discrete studies exploring transfer and persistence of soils and sediments on footwear and diatomaceous earth adhered to clothing in forensically pertinent scenarios. Variables including sediment type, foot position, clothing type, and body positioning were also explored throughout. Both experiments incorporated a field-based methodology during the sampling effort. Photographs were collected of an initial transfer sample and of a retained assemblage following hours, days, and up to one-week of wear, facilitating macroscopic assessment of trace evidence dynamics. All images were processed using accessible, open-source software before spatial analysis of evidence distribution within and temporal assessment (% retention) upon each evidential surface. The results highlighted consistent loss of transferred sediment from footwear with significantly greater retention of loamy clay soil than dune sand which was absent beyond 24 h of wear. Loss was not influenced by wearer gait but was more rapid from those areas of the shoe sole in direct contact with the ground. Diatomaceous earth was retrieved from all three clothing types tested after one week - significant losses of material occurred before 48 h with a consistent assemblage identified beyond this. Denim was significantly more effective than acrylic and fleece for diatomaceous earth retention and significantly more material was lost from clothing worn on the lower body. These findings highlight the value of using visual environmental markers and a macroscopic analytical approach during the investigation of environmental trace dynamics. The methodology offers a novel, non-destructive assessment of soil and diatom transfer and persistence, complementing more extensive laboratory-based examinations to ensure the development of a well-rounded research base within the forensic sciences.

Towards more relevance in forensic science research and development.

Many different issues have been identified in forensic science for more than 10 years. While quality management has often been suggested as a path forward, research is generally considered as an essential part of the solution. Through an overview of current forensic science research, this paper aims at evaluating if and how research answer the challenges forensic science is currently facing. While forensic related publications have massively increased over the years, approximately half of the publications were published in non-forensic sources, indicating that forensic science research tends to be led by other disciplines. Over the years, forensic science research has remained largely oriented towards methodological and technological development rather than relevance to the forensic science discipline and practice. Practical implementation of the techniques is rarely discussed from a forensic perspective, and thus research rarely move from the "proof-of-concept" stage to its utilisation in case investigation. The digital transformation also generated a massive increase of data, making it challenging to find the relevant pieces of information in the mass of "forensic" publications available on-line. Thus, we propose to refocus forensic science research on forensic fundamental and practical questions to strengthen the discipline and its impact on crime investigation and security issues. Our propositions represent an incentive to further discuss forensic science research and knowledge transmission through the definition of a common culture within the community, focusing on common fundamental knowledge such as a better understanding of the concept of trace and its case-based information content.

Assessment of deep convolutional neural network models for species identification of forensically-important fly maggots based on images of posterior spiracles.

Forensic entomology is the branch of forensic science that is related to using arthropod specimens found in legal issues. Fly maggots are one of crucial pieces of evidence that can be used for estimating post-mortem intervals worldwide. However, the species-level identification of fly maggots is difficult, time consuming, and requires specialized taxonomic training. In this work, a novel method for the identification of different forensically-important fly species is proposed using convolutional neural networks (CNNs). The data used for the experiment were obtained from a digital camera connected to a compound microscope. We compared the performance of four widely used models that vary in complexity of architecture to evaluate tradeoffs in accuracy and speed for species classification including ResNet-101, Densenet161, Vgg19_bn, and AlexNet. In the validation step, all of the studied models provided 100% accuracy for identifying maggots of 4 species including Chrysomya megacephala (Diptera: Calliphoridae), Chrysomya (Achoetandrus) rufifacies (Diptera: Calliphoridae), Lucilia cuprina (Diptera: Calliphoridae), and Musca domestica (Diptera: Muscidae) based on images of posterior spiracles. However, AlexNet showed the fastest speed to process the identification model and presented a good balance between performance and speed. Therefore, the AlexNet model was selected for the testing step. The results of the confusion matrix of AlexNet showed that misclassification was found between C. megacephala and C. (Achoetandrus) rufifacies as well as between C. megacephala and L. cuprina. No misclassification was found for M. domestica. In addition, we created a web-application platform called thefly.ai to help users identify species of fly maggots in their own images using our classification model. The results from this study can be applied to identify further species by using other types of images. This model can also be used in the development of identification features in mobile applications. This study is a crucial step for integrating information from biology and AI-technology to develop a novel platform for use in forensic investigation.

Use of micro, capillary, and nano liquid chromatography for forensic analysis.

The use of micro, capillary, and nano liquid chromatography systems for forensic analysis has excellent potential. In a field where sample size is often limited, several studies have presented the viability of capillary columns with microflow and nanoflow, and when using mass spectrometric analysis limits of detection can be improved. Reduction in flow rates result in significant reduction in operating costs. Recent advances in miniaturized liquid chromatography systems also aim at in-laboratory and on-site detection, which have already been applied to forensic drug cases. This critical review will discuss the advantages, disadvantages, and applicability of microflow and nano liquid chromatography. In this regard, included in this article is a discussion of some promising areas not yet applied to forensic research.

A low-cost chemical and optical approach to develop latent fingermarks on silver mirror surfaces.

The development of fingermarks on reflective surfaces is often a challenge regarding the photography of images with overlapping lines, low contrast and reflections, especially considering that many forensic laboratories are supplied only with basic instrumentation for fingerprint analysis. The present study overviews these difficulties and proposes a combination of chemical and optical procedures, using low-cost products and equipment, to develop fingermarks on silver mirror surfaces. The chemical treatment promotes the delimitation of the substrate, transforming the reflective surface into a transparent surface. The results were statistically analyzed, indicating quality improvement of natural fingermarks pictures taken with standard digital camera on transparent surface. There was good observation of details and minutiae, even for samples recovered several days or weeks after deposition. The suggested method substantially modifies the composition of the substrate without any contact with the fingermark, preserving its characteristics and properties. Like other nondestructive methodologies, this approach could be prioritized over methods that directly change the evidence itself and allows for the photography of the fingermark in unaltered condition. Lastly, it does not impact on the efficiency of subsequent exams.

Assessment of the knife penetration resistance of single and double-layer metal reinforced fabrics.

Textile structures are considered as the main component of protective clothing against the penetration of sharp objects. In the current research work, woven fabrics reinforced with metal threads as weft yarn were designed with various weave patterns including Twill, Satin, and Hopsack, and by using a weft-backed weaving structure. The mentioned reinforced samples were produced by altering the diameter and number of metal threads in each fabric structure. Assessment of fabric resistance against bending and sharp object penetration reveals that although the application of metal thread improves the fabric resistance against sharp object penetration, it leads to an increase in the fabric stiffness. According to the results, the influence of the number of metal threads on the penetration resistance was considerably higher than the metal thread diameter. However, more increase in the fabric's bending stiffness was observed with the rise of metal thread's diameter compared to the number of metal threads. According to the obtained outcomes, weave structure is an effective parameter that changes fabric's resistance against penetration. In this regard, weave patterns with more firmness that limit the yarn movement during the indentation of the sharp object present higher protection ability. Furthermore, the increment of fabric density enhances the resistance against penetration. In this study, the resistance of two-layer samples with various orientations angle of 0°/90° and -45°/+45° were probed, as well. Outcomes confirmed that two-layer samples resist better than single-layer sample against sharp object penetration due to the formation of a grid of metal threads. Among two studied fabrics' orientation angles, the sample with the angle of -45°/+45° presents greater penetration resistance.

Biomechanical assessment of various punching techniques.

Punches without the use of instruments/objects are a common type of body violence and as such a frequent subject of medicolegal analyses. The assessment of the injuries occurred as well as of the potential of the assault to produce severe body harm is based on objective traces (especially the documented injuries of both parties involved) as well as the-often divergent-descriptions of the event. Quantitative data regarding the punching characteristics that could be used for the assessment are rare and originate mostly in sports science. The aim of this study was to provide physical data enabling/facilitating the assessment of various punching techniques. A total of 50 volunteers took part in our study (29 males and 21 females) and performed severe punches with the fist, with the small finger edge of the hand (karate chop), and with the open hand with both the dominant and the non-dominant hands in randomized order. The strikes were performed on a boxing pad attached to a KISTLER force plate (sampling frequency 10,000 Hz) mounted on a vertical wall. The punching velocity was defined as the hand velocity over the last 10 cm prior to the contact to the pad and ascertained by using a high-speed camera (2000 Hz). Apart from the strike velocity, the maximum force, the impulse (the integral of the force-time curve), the impact duration, and the effective mass of the punch (the ratio between the impulse and the strike velocity) were measured/calculated. The results show a various degree of dependence of the physical parameters of the strikes on the punching technique, gender, hand used, body weight, and other factors. On the other hand, a high degree of variability was observed that is likely attributable to individual punching capabilities. In a follow-up study, we plan to compare the "ordinary" persons with highly trained (boxers etc.) individuals. Even though the results must be interpreted with great caution and a direct transfer of the quantitative parameters to real-world situations is in general terms not possible, the study offers valuable insights and a solid basis for a qualified forensic medical/biomechanical assessment.

Solvent-free, Noncontact Electrostatic Sampling for Rapid Analysis with Mass Spectrometry: Application to Drugs and Explosives.

A hand-held Van de Graaf generator is used to apply a high voltage, negligible current electrostatic potential to a wire mesh positioned in close proximity to a particle-laden surface in order to collect those particles for analysis. The electrostatic field effects transfer particles to the mesh without a requirement for mechanical contact between mesh and surface. Analysis of chemicals present in the sampled particles is completed by thermal desorption electrospray ionization. The utility of the method for noncontact sampling is demonstrated using solid drug powder samples, and inorganic explosives dispersed either on solid surfaces or in sand/soil in order to simulate common interfering matrices that might be encountered in the forensic environment. A metal mesh sampling substrate is utilized instead of traditional polymer-based swabs in order to permit thermal desorption at higher temperatures. The method leaves no visible trace of sampling leaving details such as a fingerprint image unperturbed, as demonstrated using fluorescence photography. Direct sampling of trace particles from hard surfaces and skin documents flexibility in the choice of sampling substrates, desorption temperatures, and sampling times. The potential of the device for use in forensic analyses is detailed.

An investigative strategy for assessment of injuries in forensic anthropology.

In a forensic context, identification of skeletal injuries' and traumas' timing may be of fundamental relevance to understand the events related to the life and death of an individual. In this study, we propose a new evaluation form to facilitate the detection of traumas and interpret them as ante-, peri- or post-mortem injuries. We describe the use of this form with the analysis of two skeletonized individuals. Bone injuries on their skeletons were caused by diverse sharp weapons and differed for the timing they have occurred, as revealed by macroscopic, radiographic and microscopic assays. Thanks to its completeness and user-friendly approach, the evaluation form here proposed may greatly facilitate the analysis and interpretation of injuries found on skeletons under forensic investigation.

Development and validation of a systematic approach for the quantitative assessment of the quality of duct tape physical fits.

Duct tape is a common type material found at crime scenes such as sexual assaults, murders, kidnappings, and bombings. During the examination of a known and questioned item, a 3D realignment along their edges is known as a physical fit and is often regarded as conclusive evidence that the items were once part of a single object. The conclusion of a fit between edges relies on the examiner's judgment to identify distinctive features across the tape ends. However, there are currently no consensus-based methodologies or standards to inform their opinions. This study developed a practical method to qualify and quantify tape end match features using edge similarity scores (ESS) and provided an empirically demonstrable basis to assess the significance of duct tape fracture fits. ESS were calculated as the proportion of observed matching sections per scrim bins across the fractured edge, providing a quantifiable criterion and means for a systematic peer review process. A set of 2280 duct tape end comparisons were analyzed for the validation study. The probative value of physical fits was evaluated through similarity metrics, error rates, and score-based likelihood ratios. The effects of separation method, stretching, and tape grade on the distribution of ESS and the overall accuracy are reported. The accuracy ranged from 84.9 % (higher quality hand-torn set) to over 99 % (low and mid-quality sets). No false positives were reported for any of the sets examined. On average, ESS higher than 80 % provided a score likelihood ratio (SLR) that supported the conclusion of a match, and ESS lower than 25 % provided an SLR supporting the conclusion of non-match.

Forensic gait analysis - Morphometric assessment from surveillance footage.

Following the technological rise of surveillance cameras and their subsequent proliferation in public places, the use of information gathered by such means for investigative and evaluative purposes sparked a large interest in the forensic community and within policing scenarios. In particular, it is suggested that analysis of the body, especially the assessment of gait characteristics, can provide useful information to aid the investigation. This paper discusses the influences upon gait to mitigate some of the limitations of surveillance footage, including those due to the varying anatomical differences between individuals. Furthermore, the differences between various techniques applied to assess gait are discussed, including biometric gait recognition, forensic gait analysis, tracking technology, and marker technology. This review article discusses the limitations of the current methods for assessment of gait; exposing gaps within the literature in regard to various influences impacting upon the gait cycle. Furthermore, it suggests a 'morphometric' technique to enhance the available procedures to potentially facilitate the development of standardised protocols with supporting statistics and database. This in turn will provide meaningful information to forensic investigation, intelligence-gathering processes, and potentially as an additional method of forensic evaluation of evidence.

Comparative Assessment of a Novel Photo-Anthropometric Landmark-Positioning Approach for the Analysis of Facial Structures on Two-Dimensional Images.

Positioning landmarks in facial photo-anthropometry (FPA) applications remains today a highly variable procedure, as traditional cephalometric definitions are used as guidelines. Herein, a novel landmark-positioning approach, specifically adapted for FPA applications, is introduced and, in particular, assessed against the conventional cephalometric definitions for the analysis of 16 landmarks on ten frontal images by two groups of examiners (with and without professional knowledge of anatomy). Results showed that positioning reproducibility was significantly better using the novel method. Indeed, in contrast to the classic approach, very low landmark dispersions were observed for both groups of examiners, which were usually below the strictest clinical standards (i.e., 0.575 mm). Furthermore, the comparison between the two groups of examiners highlighted higher dispersion consistencies, which supported a higher robustness. Thus, the use of an adapted landmark-positioning approach proved to be highly advantageous in FPA analysis and future work in this field should consider adopting similar methodologies.

Memory at the Sharp End: The Costs of Remembering With Others in Forensic Contexts.

In many applied contexts where accurate and reliable information informs operational decision-making, emergency response resource allocation, efficient investigation, judicial process, and, ultimately, the delivery of justice, the costs of unfettered conversational remembering can be high. To date, research has demonstrated that conversations between co-witnesses in the immediate aftermath of witnessed events and co-witness retellings of witnessed events often impair both the quality and quantity of information reported subsequently. Given the largely negative impact of conversational remembering on the recall of both individual witnesses and groups of witnesses in this context, this review explores the reasons why these costs occur, the conditions under which costs are exacerbated, and how, in practical terms, the costs can be reduced in order to maximize the accuracy and completeness of witness accounts.

The application of low-altitude near-infrared aerial photography for detecting clandestine burials using a UAV and low-cost unmodified digital camera.

Aerial photography and remote sensing has been carried out in the past by numerous different platforms, utilizing imaging from across the electromagnetic (EM) spectrum to gain information about the earth. These techniques have additionally been found effective when locating mass graves and single clandestine graves created by perpetrators when concealing homicide victims. Applications for performing aerial photography and remote sensing are costly and therefore usually overlooked by police investigators, resulting in employing more contemporary geophysical methods for locating burials. Recent advances in technology however have seen the development of small Unmanned Aerial Vehicles (UAVs) for aerial photography which can be executed at low altitude and controlled remotely from the surface. This development has introduced low-cost approaches in detecting surface features, commonly utilised in the archaeological field for its accuracy in detecting anomalies, particularly when using near-infrared (NIR) photography. NIR aerial images have been shown to expose cropmarks of historical value which are unnoticeable in conventional colour photography, deriving from the visual area of the EM spectrum. However, little attempt has been made to investigate the practice of NIR photography to detect clandestine graves using low-cost aerial platforms in the form of UAVs. This paper considers adopting a low-cost and non-invasive approach to detect clandestine graves through the implementation of a small UAV and an unmodified GoPro camera fixed with a near-infrared filter. The results presented here have recognised real-time suitability for using UAVs as an aerial photographic platform in the forensic archaeological field as well as noting the advantage of NIR photography as an ongoing technique for discriminating recent graves from their surroundings.

Forgotten evidence: A mixed methods study of why sexual assault kits (SAKs) are not submitted for DNA forensic testing.

Throughout the United States, hundreds of thousands of sexual assault kits (SAKs) (also termed "rape kits") have not been submitted by the police for forensic DNA testing. DNA evidence can help sexual assault investigations and prosecutions by identifying offenders, revealing serial offenders through DNA matches across cases, and exonerating those who have been wrongly accused. In this article, we describe a 5-year action research project conducted with 1 city that had large numbers of untested SAKs-Detroit, Michigan-and our examination into why thousands of rape kits in this city were never submitted for forensic DNA testing. This mixed methods study combined ethnographic observations and qualitative interviews to identify stakeholders' perspectives as to why rape kits were not routinely submitted for testing. Then, we quantitatively examined whether these factors may have affected police practices regarding SAK testing, as evidenced by predictable changes in SAK submission rates over time. Chronic resource scarcity only partially explained why the organizations that serve rape victims-the police, crime lab, prosecution, and victim advocacy-could not test all rape kits, investigate all reported sexual assaults, and support all rape survivors. SAK submission rates significantly increased once criminal justice professionals in this city had full access to the FBI DNA forensic database Combined DNA Index System (CODIS), but even then, most SAKs were still not submitted for DNA testing. Building crime laboratories' capacities for DNA testing and training police on the utility of forensic evidence and best practices in sexual assault investigations can help remedy, and possibly prevent, the problem of untested rape kits. (PsycINFO Database Record

Quantitative assessment of similarity between randomly acquired characteristics on high quality exemplars and crime scene impressions via analysis of feature size and shape.

Forensic footwear evidence can prove invaluable to the resolution of a criminal investigation. Naturally, the value of a comparison varies with the rarity of the evidence, which is a function of both manufactured as well as randomly acquired characteristics (RACs). When focused specifically on the latter of these two types of features, empirical evidence demonstrates high discriminating power for the differentiation of known match and known non-match samples when presented with exemplars of high quality and exhibiting a sufficient number of clear and complex RACs. However, given the dynamic and unpredictable nature of the media, substrate, and deposition process encountered during the commission of a crime, RACs on crime scene prints are expected to exhibit a large range of variability in terms of reproducibility, clarity, and quality. Although the pattern recognition skill of the expert examiner is adept at recognizing and evaluating this type of natural variation, there is little research to suggest that objective and numerical metrics can globally process this variation when presented with RACs from degraded crime scene quality prints. As such, the goal of this study was to mathematically compare the loss and similarity of RACs in high quality exemplars versus crime-scene-like quality impressions as a function of RAC shape, perimeter, area, and common source. Results indicate that the unpredictable conditions associated with crime scene print production promotes RAC loss that varies between 33% and 100% with an average of 85%, and that when the entire outsole is taken as a constellation of features (or a RAC map), 64% of the crime-scene-like impressions exhibited 10 or fewer RACs, resulting in a 0.72 probability of stochastic dominance. Given this, individual RAC description and correspondence were further explored using five simple, but objective, numerical metrics of similarity. Statistically significant differences in similarity scores for RAC shape and size were consistently detected for three of the five metrics (modified phase only correlation, Euclidean distance, and Hausdorff distance). Conversely, a single metric (the matched filter) expressed the least dependence between score and both shape and size. Moreover, for all crime-scene-like RACs with coincidental association in position, the matched filter produced the greatest discrimination potential in sorting known matches and known non-matches. Despite this demonstrated success, numerical metrics of similarity are not without limitations, and the remainder of this work provides commentary on the difficulties associated with using objective metrics when faced with segmentation, incomplete information, and low signal-to-noise ratios.