Use of Squid as an Alternative to Human Skin for Studying theDevelopment of Hit Marks on Clothes

Abstract

The development of latent skin impressions on a variety of fabrics (cotton, rayon, polyester, nylon, and acrylic fabrics in five colors; white, black, yellow, blue and red) has been studied. Squid soaked in artificial sweat solution or de-ionized water was used as an alternative to human skin to make skin impressions on the fabric. A piece of squid was subjected to a constant force, to transfer the skin components onto the fabric. The fabrics bearing the skin impressions were treated with various reagents such as ninhydrin, 1,8-diazafluoren-9-one (DFO), 1,2-indanedione/ Zn (1,2-IND/Zn), Amido black and Hungarian red, to know the most effective method for developing the skin impressions on the fabrics. Comparing the sensitivity of the reagents, stronger development was observed from the impressions made with the artificial sweat soaked squid than the de-ionized water soaked squid. These results show that the development quality of the latent hit mark is influenced by the sweat, as well as other skin components. Also, the development efficiency of the reagents varied depending on the chemistry, color and texture of the fabric. Therefore, before the development of skin impressions on the evidence fabrics, it is suggested to perform a preliminary experiment with different methods on a similar fabric to decide the most sensitive method.