Efficacy of ring precipitin and precipitation electrophoresis tests for species identification of old dried blood stains

Abstract

The present paper is concerned with a comparative study of ring precipitin and precipitation electrophoresis tests in the species identification of dried blood stains of various ages, spanning over a period of 1 day to 10 years. In this connection, though most authorities claim that these two tests, particularly the precipitation electrophoresis test are very efficient in the species identification, yet so far very few literatures have appeared regrading the details of their works, including the number of specimens and their respective ages. I am, therefore, presenting here this paper with a view to fulfilling this lacuna in view of the fact that the authorities of law and justice insist on the authenticity of the tests as well as their relevance to crime investigation. The present study comprises testing 4,000 dried blood specimens (cloth-stained) of various ages, for species identification by ring precipitin and precipitation electrophoresis methods. The specimens were stored at room temperature which, in a country like India, varies from 4°C to 45°C with average humidity. I have observed from this study that the two tests are found to give satisfactory and promising results, the precipitation electrophoresis test being more sensitive and more dependable than the ring precipitin test in relation to ageing of the blood stains.