BulletProof Probabilistic Genotyping Tool
Why BulletProof and Probabilistic Genotyping?
BulletProof is the latest addition to the arsenal of probabilistic genotyping tools providing a Frequentist and Bayesian methodology to resolve complex mixtures and provide mixture deconvolution.
Years ago, the ISFG published recommendations for the interpretation of low-level mixtures when dropout is possible (Gill et al. 2012). Probabilistic genotyping tools provide the ability to utilize all data above the laboratory’s empirically determined analytical threshold by accounting for “uncertainty” wherein we incorporate a probability of allelic drop-out, drop-in (and if warranted, alternate hypotheses including the ability to account for possible “related suspects”) in the LR.
Why is Probabilistic Genotyping necessary.
The trend in the type of samples Forensic Laboratories are asked to resolve, along with improved extraction methods, amplification chemistries, and improved CE instrumentation have exceeded the ability to adequately resolve mixtures using binary mixture interpretation protocols. When laboratories try to analyze highly complex mixtures, such as “touch” items with more than two contributors and stochastic data, binary methods (CPE, CPI, Modified RMP) fail miserably. With traditional binary methods, there exists no way to factor uncertainty.
Current strategies to evaluate low-level mixtures with dropout using the binary methods are insufficient. The existing CPE/CPI methods have no fundamental validity, there exist no unambiguous and rigorous mathematical proofs—it is fundamentally flawed and at best, a “stab” at the weight of the evidence.