ABSTRACT
Bloodstains can provide important information about a criminal act. These biological traces, when analyzed at murder sites, for example, can determine the dynamics of a criminal offense, the identity of a suspect, and the time at which a crime was committed. Determine the time since deposition (TSD) of these blood traces may be the first clue for the police investigators to estimate the time-lapse of a murder. During a criminal attack, the blood spilled from an injury begins the process of degradation and aging from the moment it leaves the human body and comes into contact with the physical environment. The biophysical properties (morphology and elasticity) of red blood cells (RBCs) undergo several changes when outside the human body, which can be analyzed using microscopic techniques such as atomic force microscopy (AFM). Aiming to apply the AFM/force spectroscopy techniques in the analysis of criminal traces, the present study investigated the TSD for blood smears by analyzing possible changes in the RBCs of a group of voluntary donors. Also, we investigated whether there was any difference in TSD analysis after blood smears deposition onto three different surfaces (glass, metal, or ceramic); and finally, we evaluated force×distance curves obtained from deformation of the membrane surface of RBCs as a function of time. The qualitative results apparently showed that there is no perceptible difference in the structure of RBCs when AFM images were analyzed by simple visual comparison over 28 days (T0-T5). Nevertheless, our quantitative results, measured by AFM, demonstrated the increasing trend of the measurements, such as average height (µm), perimeter (µm), area (µm2) and volume (µm3) of these cells during that period. Additionally, the type of surface of bloodstain deposition should be considered during analyses for the TSD, and the results obtained on glass, metal, or ceramic supports showed significant differences. Therefore, the use of force spectroscopy to obtain force×distance curves for the forensic science approach has been shown to have applicability for the calculation of TSD in the RBCs present in the blood smears. In spite of the promising observations obtained, the use of AFM in crime scenes still requires the expansion and development of more studies for a definitive evaluation of the TSD for blood spots.
Subject(s)
Blood Stains , Erythrocytes/ultrastructure , Microscopy, Atomic Force , Adult , Cell Membrane , Ceramics , Elasticity , Female , Forensic Medicine/methods , Glass , Humans , Image Processing, Computer-Assisted , Male , Metals , Software , Surface Properties , Time Factors , Young AdultABSTRACT
Se examina cómo los analistas pueden ayudar a responder a los retos emergentes que enfrentan las instituciones policiales y de persecución en la región: la necesidad de proactividad y mayor eficacia. El Método que se sigue es la descripción de la función y las tareas "tradicionales" del analista criminal, y la revisión de las tendencias y requisitos asociados al diseño y ejecución de políticas criminales eficaces. La búsqueda de determinantes de mejores resultados y la incursión en evaluaciones de las acciones policiales y de persecución penal representan desafíos "nuevos", que deberían abordar los analistas, con un uso intensivo del Método científico, en especial en la observación, testeo y comprobación de qué realmente funciona o no. Se advierte, entonces, una transición que interpela el papel del analista y del análisis: desde la "gestión de información" a la "gestión de conocimiento" en las organizaciones.
This article examines how analysts can assist police and prosecution institutions in the region to meet emerging challenges, thus the need for proactivity, enhanced efficiency and improved efficacy. The method used is the description of the criminal analyst's relevant function and "traditional" tasks, along with a trend review and the revision of requisites associated to design and enforcement of effective criminal policies. The search for determinants of better results along with an incursion into police and criminal prosecution actions represent "new provocations" to be addressed with an intensive use of the scientific method, particularly in dealing with observation, testing and verification of what actually works or does not work. Then, a transition that questions the role of the analyst and the analysis itself is observed from "information management" to "knowledge management" in the organizations.
Examina-se como os analistas podem ajudar a responder aos desafios emergentes que enfrentam as instituições policiais e da persecução na região: a necessidade da proatividade e da maior eficácia. O Método seguido é a descrição da função e as tarefas "tradicionais" do analista criminal, e a revisão das tendências e das exigências associadas ao projeto e execução de políticas criminais eficazes. A busca das determinantes de melhores resultados e da incursão nas avaliações das ações policiais e da persecução penal representa desafios "novos", que deveriam ser abordados pelos analistas, com um uso intensivo do Método científico, em especial na observação, nos testes e na verificação de aquilo que funciona realmente. Apercebe-se, então, uma transição que interpela o papel do analista e da análise: desde a "gestão da informação" à "gestão do conhecimento" nas organizações.
