Skip to content

Towards a likelihood ratio approach for bloodstain pattern analysis

Journal: Forensic Science International
Published: 2022
Primary Author: Tong Zou
Secondary Authors: Hal Stern

In this work, we explore the application of likelihood ratio as a forensic evidence assessment tool to evaluate the causal mechanism of a bloodstain pattern. It is assumed that there are two competing hypotheses regarding the cause of a bloodstain pattern. The bloodstain patterns are represented as a collection of ellipses with each ellipse characterized by its location, size and orientation. Quantitative measures and features are derived to summarize key aspects of the patterns. A bivariate Gaussian model is chosen to estimate the distribution of features under a given hypothesis and thus approximate the likelihood of a pattern. Published data with 59 impact patterns and 55 gunshot patterns is used to train and evaluate the model. Results demonstrate the feasibility of the likelihood ratio approach for bloodstain pattern analysis. The results also hint at some of the challenges that need to be addressed for future use of the likelihood ratio approach for bloodstain pattern analysis.

Related Resources

An Open-Source Implementation of the CMPS Algorithm for Assessing Similarity of Bullets

An Open-Source Implementation of the CMPS Algorithm for Assessing Similarity of Bullets

In this paper, we introduce the R package cmpsR, an open-source implementation of the Congruent Matching Profile Segments (CMPS) method developed at the National Institute of Standards and Technology (NIST)…
A Data-Driven Approach to Model the Generation Process of Bloodstain Patterns

A Data-Driven Approach to Model the Generation Process of Bloodstain Patterns

This poster was presented at the 106th International Association for Identification
Error Rate Methods for Forensic Handwriting Identification

Error Rate Methods for Forensic Handwriting Identification

Presentation is from the 106th International Association for Identification (IAI) Annual Educational Conference
Measuring Proficiency among Latent Print Examiners: A Statistical Approach from Standardized Testing

Measuring Proficiency among Latent Print Examiners: A Statistical Approach from Standardized Testing

This presentation is from the 74th Annual Scientific Conference of the American Academy of Forensic Sciences