Background Evidence can be defined as the object’s availability and/or information that indicates whether a belief or proposition is true or valid. Gunshot residue (GSR) is an important evidence that can serve many roles in ballistic investigation such as shooting distance, type of firearm and ammunition used in shooting related to GSR. However, due to minimal amount of GSR that can be found in crime scene, suitable methods and technique are required in order to obtain the information from the evidence. This action is also known as evidence recovery. When a firearm is fired, soot or particles are discharged from any opening of the firearm and deposited at the vicinity of point of shooting. Results This study emphasized on the examination of the soot/particles produced and pattern distribution of GSR deposited on white cotton cloth target at varying shooting distances (from 3 to 50 cm) using a video spectral comparator. Pattern distribution and GSR particle density are the main factors in determining the shooting distances in clothing. Principle component analysis (PCA) and hierarchical clustering analysis (HCA) were used to classify firearms; the differences in the GSR pattern distribution are highly recognizable. This study showed that the relationship between the GSR particle dispersion and shooting distance was proportionally linear. The results obtained from the shooting test showed that the diameter of GSR distribution and the amount of residues being deposited from shots fired decreased at distances greater than 21 cm. Conclusion This study will help the investigators in determining the shooting distances and evaluating the firearms used. There is a promising method for examination of GSR pattern on the target material which is also important for firing distance estimation.

In forensic ballistics, gunshot residue (GSR) particles can be detected using screening or presumptive tests which are mainly focused on the chromophoric reaction. Most tests serve as an initial indication for a forensic investigator at the crime scene before instrumental analysis for definitive identification. The screening methods are known to be convenient, have fast analysis, and minimal preparation. In GSR analysis, the well-known method of detecting GSR known as the Modified Griess Test (MGT) requires acid and heat for the reaction. Therefore, this study demonstrated a new and rapid screening test named the Rapid Griess Test (RGT) for the detection of GSR. This study intends to improve the functionality of previous screening reagents in determining nitrite (NO2–), the composition present after shooting activity. To do this, chemical reagents with an amino group, 3-aminophenol, were substituted with alpha-naphthol. The experiment showed that the reactions were positive color changes using standard NO2– and real GSR samples. The diazotization reactions involving sulfanilic acid and 3-aminophenol produced azo dyes that changed the solution from colorless to orange in the presence of NO2–. The RGT reagent will make it possible to avoid using heat and the addition of acetic acids in a sample to form chromophoric reactions. Moreover, the colorimetric method using Video Spectral Comparator (VSC) showed that RGT had higher intensity of the orange color when compared to MGT.

No abstract

No abstract

No abstract