Latent lip print: A comparative study of developers

Abstract

Identification of a person is of paramount importance in a medico-legal investigation. At present more and more people use protecting lipsticks and permanent lipsticks. With these lipsticks a latent lip print is generated by contact with a surface and, like with the latent fingerprints occur, this latent lip print can be developed. This study aims to retrieve latent lip prints from various inanimate surfaces like thermocoal plate, bone china, and glass to compare the efficacy of developers i.e., fingerprint powder, Sudan III, Vermillion, and its comparison with standard lipstick prints. Current research assesses the effectiveness of particular surfaces in the retrieval of lip print in personnel identification. This study included a total of 30 subjects. Latent lip print was developed on the different inanimate surfaces by pressing the lips against the different vehicles. After collecting samples, a camel hair brush was used to retrieve all three chemicals individually by simply tapping on all three surfaces. Application of chemicals was continued until the print became clearly visible for the study. Developed latent lip print was then compared with the visible lip print. Subsequently, a standard lipstick print was developed from the same subject. All the samples were coded and graded according to the patterns suggested in the literature. Discrete (categorical) data were summarized in number and percentage and compared by chi-square (χ2) test. Analyses were performed on SPSS software (Windows version 17.0).: The overall (i.e., total of all three surfaces) favourable outcome was found highest in Fingerprint powder (58.9%) followed by Sudan III (28.9%) and Vermilion (10.0%) the least (Vermilion < Sudan III < Fingerprint powder).Comparing the overall outcomes of three developers, χ2 test showed significantly different and higher favourable outcome in Fingerprint powder as compared to both Sudan III and Vermilion (χ2=92.09, p<0.001) The study found Fingerprint powder the best developer and Thermocol plate the best surface. The findings of this study may be beneficial for investigators.