Interpreting Trace Evidence

Forensic glass examinations—A review focused on elemental spectrochemical analysis

“…A drawback of the comparison interval methods is that they do not assess the glass composition's rarity, and the results are prone to the fall‐off‐the‐cliff effect (Buzzini & Curran, 2020; Curran et al, 2020; Ramos et al, 2021). Alternatively, Bayesian approaches provide additional advantages to glass interpretation.…”

“…The prevalence of glass on members of the general population is a fundamental piece of evidence interpretation. The informative value of glass relies on experimental background surveys that have demonstrated that it is uncommon to find glass in the regular population compared to those who have come to the attention of law enforcement or have hobbies or professions where glass is often broken (Buzzini & Curran, 2020;Curran et al, 2020;Daéid et al, 2009;Jackson et al, 2013;Kim et al, 2016;O'Sullivan et al, 2011). These studies have also set the basis for which areas of clothing (surface vs. embedded areas, upper vs. lower garments) are more prone to retain randomly acquired glass fragments.…”

“…For instance, among the many factors known to influence how much glass is deposited to the recipient and for how long it remains are (a) the applied force and object used to break the glass, (b) the type and size of the window, (c) the distance from the window, (d) the retention characteristics of the clothing, (e) the post breaking activities, and (f) time elapsed between the glass breaking and the apprehension or recovery of the glass. These findings are used as a basis for various interpretation approaches (Buzzini & Curran, 2020; Curran et al, 2020).…”

“…Once submitted to the laboratory, the forensic examiner determines if the physical and optical properties and the elemental composition of the compared items are distinguishable or not and assesses the significance of the evidence at the source and activity level to assist the investigation and the trier of fact (Almirall & Trejos, 2015; Kammrath et al, 2016). The type of glass, the rarity or commonality of the compared features among questioned and known samples, as well as the number of fragments or groups of fragments recovered, their relative location, and the time since the breaking all play an essential role in the overall interpretation of the evidence when considering the context of the case (Buzzini & Curran, 2020; Kammrath et al, 2016).…”

“…In a court of law, glass evidence is often admissible because (a) it holds valid scientific foundations, (b) it has established consensus‐based standards with known performance and error rates, and (c) it has been shown to provide valuable support to the prosecutor or defense hypotheses (Almirall & Trejos, 2015; Trejos et al, 2020). For instance, a large body of knowledge exists on the occurrence of glass in the general population compared to persons involved in crimes or those who have broken glass recently (Buzzini & Curran, 2020; Curran et al, 2020; Trejos et al, 2020). Likewise, extensive studies have evaluated the factors affecting glass transfer and persistence (Curran et al, 2020).…”