Defining Patterns and Behaviours of Forward Spatter Gunshot Misting

The purpose of this research was to study forward-spatter misting patterns by shooting a firearm through a chamber of blood encased in ballistic gel to determine if there is a relationship between bloodstain pattern size as a function of distance and orientation. There is a lack of research on forward spatter, blood travelling in the direction of a bullet, as most studies focus on back spatter, blood travelling in the opposite direction of a bullet. A bullet was fired through ballistic gel containing a blood chamber, depositing bloodstains onto a large sheet of butcher paper as the target surface. In total, there were 34 trials. The distances observed were 10, 20, 40, and 80 cm, the angles tested were 30°, 60°, and 90°. The orientation between the ballistic gel and paper target varied. A criterion was established to observe the overall area and symmetry of the bloodstain patterns. Statistical analyses indicated a negative linear relation relationship between the bloodstain pattern size and the paper’s angle and distance (R2 = 0.78) and the vertical symmetry of the bloodstain (R2 = 0.87). The orientation between the ballistic gel and paper target can impact the bloodstain pattern’s symmetry and size.

Features of establishing the presence of blood in old stains by the method of thin-layer vertical chromatography

Due to the fact that the bloodstain pattern analysis takes the first place in the structure of the study of biological objects, the question of the study of blood patterns is relevant today. The main task (that will allow to solve the following, which puts the investigation before the experts), is to prove that these patterns, which are examined, contain blood, (regardless of their remoteness, attempts to destroy patterns of blood), find out its types or refute traces of blood. If the expert fails to prove the presence of blood, he must refuse to address the following issues. Otherwise, the expert may obtain results that will ultimately lead him to an erroneous conclusion. The article considers options for extraction of old blood stains in order to establish the presence of blood by the method of thin-layer vertical chromatography. This question is still relevant, as biological material can change under the influence of environmental factors and time and this can be an obstacle to establishing the fact of its presence on physical evidence, and also it can do harm to the quality of the study and the correctness of the conclusions, made as a result of the study. In order to select substances, that could provide rapid extraction of old blood stains, a study was performed using weak solutions of alkalis and acids and subsequent determination of the presence of blood by thin layer vertical chromatography. In immunological studies, there have been cases where blood crusts on non-hygroscopic surfaces under the influence of natural factors (such as high temperatures and direct sun rays) have not been extracted in saline and distilled water for several days. In addition, when using known blood samples in the reactions, the dependence of the saturation of the extracts on the age of the samples and the time of their extraction. These observations prompted researches in the sector of biological research and accounting of the Cherkasy NDEKTs of the Ministry of Internal Affairs on methods for extracting old blood stains, which would allow to detect blood in the shortest possible time by the method of thin-layer vertical chromatography.

A DNA-based method for distinction of fly artifacts from human bloodstains

Fly artifacts resulting from insect activity could act as confounding factors on a crime scene and interfere with bloodstain pattern analysis interpretation. Several techniques have been proposed to distinguish fly artifacts from human bloodstains based on morphological approach and immunological assay, but a DNA-based method has not been developed so far. Even if in forensic genetic investigations the detection of human DNA is generally the primary goal, fly artifacts can provide useful information on the dynamics of crime events. The present study provides a molecular method to detect fly DNA from artifacts deposited by Calliphora vomitoria after feeding on human blood through the analysis of the mitochondrial cytochrome oxidase gene subunit I (COI). Fly artifacts originated from digestive process and of different morphology spanning from red and brownish/light brown, circular and elliptical stains to artifacts with sperm-like tail or a tear-shaped body were collected. The COI amplification was successfully obtained in 94% of fly artifact samples. The method showed high sensitivity and reproducibility, and no human DNA contamination was observed, offering specificity for use in confirmatory test. This molecular approach permits the distinction of fly artifacts from genuine bloodstains and the identification of fly’s species through the COI region sequencing by protocols usually applied in forensic genetic laboratories.

Variations in the Impact Spatter Patterns due to Blunt Weapons Inflicted by Different Gender and Age Groups

Bloodstain pattern analysis makes use of the mechanics of bloodstains to estimate the time, nature and the sequence of events at the crime scene. In this study, a quantitative methodology was developed which includes manually calculating the average size of the bloodstains and the synthetic bloodstains to distinguish the impact stain patterns created by different gender and age groups using the two blunt weapons. Impact stains were created by hitting sponges soaked in blood and synthetic blood using a hammer and a cricket bat. A smaller bloodstain size was observed of the group of males aged between 18 to 30 years. Greater amount of spatter and the distribution of the blood spatter were observed with the bat as compared to hammer due to larger surface area of bat. Cast off patterns were studied and were observed to be produced only by the bat which can be attributed to its higher surface area. Results showed difference in the bloodstain diameter produced from human blood and synthetic blood evaluating if the synthetic blood is suitable for use, as well as variation in the average stain size between produced by the four groups using both the fluids.

Application of DNA Containing Forensic Blood Substitute in the Bloodstain Pattern Analysis

We were able to diversify blood substitutes that emphasized the existing physical characteristics by adding the synthetic DNA, which was designed and produced in this study, to developed blood substitute. By doing so, we could improve the availability of developed blood substitute to the point where it can be identified similarly as in DNA analysis from the human blood.

Recognition of overlapping elliptical objects in a binary image

Recognition of overlapping objects is required in many applications in the field of computer vision. Examples include cell segmentation, bubble detection and bloodstain pattern analysis. This paper presents a method to identify overlapping objects by approximating them with ellipses. The method is intended to be applied to complex-shaped regions which are believed to be composed of one or more overlapping objects. The method has two primary steps. First, a pool of candidate ellipses are generated by applying the Euclidean distance transform on a compressed image and the pool is filtered by an overlaying method. Second, the concave points on the contour of the region of interest are extracted by polygon approximation to divide the contour into segments. Then, the optimal ellipses are selected from among the candidates by choosing a minimal subset that best fits the identified segments. We propose the use of the adjusted Rand index, commonly applied in clustering, to compare the fitting result with ground truth. Through a set of computational and optimization efficiencies, we are able to apply our approach in complex images comprised of a number of overlapped regions. Experimental results on a synthetic data set, two types of cell images and bloodstain patterns show superior accuracy and flexibility of our method in ellipse recognition, relative to other methods.