Improved Area of Origin Estimation for Bloodstain Pattern Analysis Using 3D Scanning

Abstract

An important component of crime scene reconstruction is bloodstain pattern analysis (BPA). Where BPA concerns impact patterns, estimating the area of origin is critical information for scene reconstruction. Traditionally, this is achieved by measuring individual bloodstains and performing trigonometric calculations; however, 3D scanning has been proposed as a viable alternative for overcoming logistical and practical concerns with the manual method. Therefore, this project aimed to establish whether the FARO Focus 3D scanner and FARO Zone 3D software can improve the accuracy of area of origin estimates relative to the manual method. We created a series of eight bloodstain impact patterns and performed paired analysis using the two methods to estimate areas of origin for each pattern. Our data suggested that FAROderived estimates were generally more accurate than using the manual method. FARO-estimated heights of origin areas were generally closer to the true distance. Both methods underestimated the distance from the wall for most patterns originating 150mm or greater from the wall, but overestimated distances for patterns originating closer to the wall. The degree to which distances were underestimated increased significantly the further the blood source was from the wall and was greater for FARO-derived estimates. The results of this research contribute to the validation of these instruments for operational implementation for BPA and should be considered alongside the practical benefits of 3D scanning relative to manual methods. Further, 3D scanning can provide reliable BPA reconstruction documentation for technical review and court presentation.

A Study of 3D Digitisation Modalities for Crime Scene Investigation

“…We note that the particular structured light scanner is employed with a pretty old sensor, similar to Kinect-v1; therefore, lower precision was somewhat expected. Blood pattern analysis is also considered in [15], where a high-end scanner (FARO Focus 3D) is combined with high-resolution photography provided by a DSLR. The photos were stitched to the scan using the Faro Zone 3D software.…”

Assessing iPhone LiDAR & Recon‐3D for determining area of origin in bloodstain pattern analysis

“…3D‐printed square scales (10 × 10 cm and 20 × 20 cm) equipped with bubble levels were placed around clusters of useful stains and were chosen based on previous research suggestions and recommendations (Figure 9). For reliable results, it was important that well‐formed symmetrical ellipses indicating directionality were selected from various locations in the scene, aiming to capture a wide spread of stains within each selected cluster [5, 25]. After all the square scales were placed and secured with tape, the bloodstains were photographed using a Nikon D7100 camera with a 1:1 60 mm macro lens (Figure 10).…”

“…The ellipse tracing process was repeated on each cluster (three to five clusters per impact, depending on the individual impact patterns), choosing only well-formed ellipses traveling in the same general direction (Figure 14). Once FARO Zone 3D had at least two photographs with ellipses drawn, it automatically calculated the estimated AO [19,25,26].…”

A Virtual, 3D Multimodal Approach to Victim and Crime Scene Reconstruction

“…Three-dimensional models have also found applications in crime scene investigations that involve quantitative analysis. For instance, they have been utilized in bloodstain pattern analyses in 3D [134][135][136], crash and collision investigations [101,130,137] as well as bullet trajectory analysis [101,137]. These applications leverage the capabilities of 3D models to provide enhanced insights and quantitative data for a more comprehensive analysis of the crime scene.…”