CURRENT TRENDS IN HAPTOGLOBIN PHENOTYPE DETERMINATION IN FORENSIC INVESTIGATION OF BLOOD EVIDENCE

Abstract

The determination of haptoglobin phenotypes in bloodstains is widely applied in forensic examinations, particularly in cases of disputed parentage, possible child substitution, and limited or inconclusive ABO blood group results. This study aimed to evaluate the influence of bloodstain age and environmental factors on the stability and reliability of haptoglobin phenotype detection. Blood samples were obtained from healthy volunteers (18–60 years) and analyzed in native blood and in dried bloodstains deposited on paper, cotton, wool, and blended fabrics. Samples were exposed to direct sunlight, humid conditions, and soil burial for defined time intervals. Results demonstrated that haptoglobin phenotype detectability is strongly dependent on both environmental exposure and substrate type. Under direct sunlight (+25 to +30°C), reliable detection was maintained for up to 3–4 days. In humid conditions (+15 to +20°C), phenotypes remained detectable for up to one month. Soil storage (+10 to +15°C) allowed identification for up to five months, after which diagnostic reliability was lost. Thus, the forensic applicability of haptoglobin phenotyping in bloodstains is determined by the nature of the substrate and the duration and conditions of environmental exposure.