Latent lip print: A comparative study of developers

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.

Cation Crosslinking-Induced Stable Copper Nanoclusters Powder as Latent Fingerprints Marker

Luminescent copper nanoclusters (Cu NCs) have shown great potential in light-emitting devices (LEDs), chemical sensing, catalysis and biological fields. However, their practical use has been restricted by poor stability, and study on the stability of Cu NCs solid powder along with the mechanism is absent. In this study, stablized Cu NCs powder was first obtained by cation crosslinking method. Compared with the powder synthesized by solvent precipitation method, the stability of Cu NCs powder crosslinked by ionic inducer Ce3+ was enhanced around 100-fold. The storage time when the fluorescence intensity decreased to 85% (T85) was improved from 2 h to 216 h, which is the longest so far. The results of characterizations indicated that the aggregation structure was formed by the binding of Ce3+ with the capping ligands of Cu NCs, which helped in obtaining Ce-Cu NCs powder from aggregate precipitation in solution. Furthermore, this compact structure could avoid the destruction of ambient moisture resulting in long-lasting fluorescence and almost unchanged physical form. This demonstrated that phosphor, with excellent characteristics of unsophisticated synthesis, easy preservation and stable fluorescence, showed great potential in light sources, display technology and especially in latent fingerprints visualization on different substrates for forensic science.

The overlapped latent fingerprint separation by using Fourier Optics (FO)

Latent fingerprints are one of the most important pieces of evidence left at a crime scene and can be linked to all individuals involved. Each person’s fingerprints are unique and permanent, becoming an ideal biometric trait for the personal identification by extracting and comparing characteristic points (minutiae) of ridges. The overlapping fingerprint cases are frequently encountered in a crime scene and causing a difficult interpretation for an investigator. The problem has been challenging for forensic scientists over a decade. The method proposed in this study for the separation of overlapped latent fingerprints is based on the well-known spatial filtering method in the Fourier Optics (FO). Instead of tackling the problem by experiment, an alternative and simple means of image processing was proposed and conducted. The working principles start form converting spatial domain patterns (an image of overlapped fingerprints) to spatial frequency domain patterns or power spectrum, filtering out unwanted components (unwanted fingerprint) by appropriate spatial filters, and finally converting the modified pattern back to spatial domain patterns (an image of suspect fingerprint). As a result, the final image is improved from its original state. The periodic pattern of ridges is the key that allows FO to be used in the separation of the overlapped fingerprints. In this work, the procedures described are simply performed by an open source software: ImageJ. The FO-based image processing technique satisfactorily demonstrated its ability to recover an individual fingerprint from overlapping fingerprints.