Expert examination of traces of blood

Methods of sexual differentiation of blood - based detection in blood leukocytes of the characteristics of a particular sex. Women chromosomes are characterized by the presence of the two sex chromosomes XX, and the men - two different chromosomes (XY). In the nuclei of cells sex chromosomes of men are in the tangle of chromosomes, and the woman's one of the sex chromosomes turns into chromatin body and one's pressing away to the periphery of the nucleus, forming processes, reminiscent of the ear drum, the racket. In the blood of men with similar education (bullock Barra beach) are much less common.
Affiliation blood man can also be set through discovery in the nuclei of cells in the Y chromosome that established under fluorescent microscopy of blood smears prepared from the investigated spots. For the male Y chromosome has a specific effect (luminescence).
Both methods can diagnose sex spots significant limitation education - six months or more. For such studies need a relatively large amount of blood - stain of blood 1.5 X 1.5 cm and more.
In the basis of differentiation of blood of an adult and fetal lie differences in physico-chemical and electrophoretic properties contained in their blood hemoglobin, which is expressed in different speed of its migration in an electrophoretic separation in agar gel or starch, and in a various degree of stability to action of alkalis (fetal hemoglobin, NRE more resistant to alkalis). Differentiation of blood of an adult from the blood of the baby is possible only up to a year and only in spots the prescription of education is not higher than 2 to 3 weeks.
Differentiation of blood of an adult and the newborn also possible by identifying in children's blood particular protein L1-fetoprotein, not in the blood of adults. The blood of adult and child can also be distinguished by the activity of certain enzymes of blood. However, this method for several reasons not yet been used in expert practice.
The establishment of the regional origin of blood is mainly based on the detection of impurities inherent in the body, which was the source of bleeding: admixture of mucus and epithelial cells of the trachea and bronchi in case of bleeding from the upper respiratory tract, impurities Kala and mucus rectum at gemorroidalnyh bleedings, elements of the mucous membrane of the uterus menstrual bleeding. The establishment of the menstrual origin of blood traces possible by identifying its specific enzyme fibrinolizinathat is not in the peripheral blood. This is possible only in the blood stains minor-old education.
Currently, attempts are being made to use to establish a regional origin of high blood tissue and organ specificity of some enzymes, sharply distinguished by its molecular structure in various organs.
The establishment of limitation of spots of blood based on the change during the "aging" of the blood properties of hemoglobin (serial his transformation from a oxyhemoglobin in methemoglobin, gelatin, carboxyhemoglobin, hemoglobulin and hematoporphyrin). Specified derived hemoglobin inherent characteristic absorption spectra. On the basis of these characteristics and promoted, taking into account the specific conditions of finding objects with traces of blood, indicative establishment of limitation education spots.
Currently, attempts are made to use to establish a prescription stains of blood observed reduction in the activity of some enzymes of blood, depending on the time elapsed since the formation of traces.
The establishment of the quantity of liquid blood and formed a spot, it is necessary to prove the death from blood loss, when checking assumptions of the crime is not in place of detection of a corpse and in certain other cases.
There is a definite correlation between the number of dry residue blood stain and quantity of liquid blood that formed this spot, - 1000 ml of liquid blood corresponds to an average of 211 g dry blood. First, determine the difference in the mass of the same areas and spots of blood and the material of the object of the carrier (pre-drying them to constant weight), which will correspond to the mass of dry blood. Then carry out a recalculation of dry residue on liquid blood. The method allows rather tentatively set the amount of blood that formed the spot.
The establishment of pregnancy and the fact ex delivery (abortion) by the blood stains based on detection in the blood of a specific hormone that appears in early pregnancy. The hormone is very resistant to stains and can diagnose pregnancy already on 8-10 day.
Diagnostics of pregnancy, the former genera and termination of pregnancy (abortion) is also possible by determining the blood of pregnant women and parturient women specific enzyme - oxytocins that appears in the blood for 4-8 weeks of pregnancy and disappearing from the blood of pregnant women about a month later after a birth of the child. Oxytocins can be detected in the blood of 2-3-month-old education. For research requires a small amount of dry blood - 3-5 mg
The basis of determining the origin of blood stain from a living person or body lies fact posthumous release in the peripheral blood of the dead body tissue enzymes not found in the blood line of the person during his life. After about 1-2 hours after the death of their level increases so that they can be detected in the blood stains from the corpse prescription for 45 days. The method is complex and not yet found a wide application in expert practice.