Expert examination of traces of blood

  • The species identification of blood
  • The definition of the blood group
  • Methods of sexual differentiation of blood
  • The presence of blood on the material evidences is a prerequisite for subsequent determination of its species and group facilities and addressing other issues. Proposed for this purpose methods are divided into preliminary (rough) and evidence-based. As a preliminary test for the presence of blood apply inspection of the object in ultraviolet rays. The proof of blood stain based on the detection of hemoglobin or its derivatives (derivatives) - hemoglobulin and hematoporphyrin. Currently in expert practice for this purpose used mainly absorption spectroscopy method, based on the ability of hemoglobin and its derivatives to absorb light waves of a certain length and form absorption spectra. For this purpose from the investigated spots prepare drugs - thread cloth or a particle spots treated with lye and the restorer (mnogomernoi ammonia), under the influence of these substances haemoglobin of the blood becomes hemoglobulin. To obtain hematoporphyrin material spots treated with concentrated sulfuric acid. For each of these substances the nature of the spectra specific quantity, location and intensity of absorption bands. Spectral study is conducted with the help of special Microspectral nozzles or spectroscope direct vision. The method is very sensitive, allows to establish the presence of blood in the footsteps of great ago. The detection range of hemoglobin or one of its derivatives proves the presence of blood in the test spot. With deep destruction of blood, for example when it charring, it is recommended to use emission spectral analysis, which is based on determination of inorganic elements typical of the blood.
    To establish the presence of blood apply various methods of chromatography - chromatography and microhematuria on paper, sylufolic plates etc. These methods are highly sensitive, sufficient simplicity and allow to explore a large number of objects. In some cases, the presence of blood can be installed by discovering her uniform elements of erythrocytes. This appears when a barely noticeable thin trail of blood on the subject with a smooth surface. Erythrocytes in such cases detected a relatively simple method of epimerase with the help of the device opaque-window.