An exercise in scientific problem-solving: Illustrating the utility of the principles of the Sydney Declaration

In forensic science, scientific problem-solving is characterized by the recognition of traces as part of iterative reasoning processes to assign meaning to those traces in order to interpret and reconstruct events. Through a set of fundamental principles, the Sydney Declaration presents a foundation of forensic science through the lens of a scientist. The distinction between a scientist and a technician may require clarification—where a prototypical technician follows a prescribed set of ‘standard operating procedures’ and may be limited in the interpretation of the resultant data, the scientist utilizes knowledge, skills, experience and imagination to identify the issue at hand and develop lines of inquiry for testing and interpretation. This case report draws on the Sydney Declaration in order to highlight the importance of learning about events from careful consideration of both obvious and less obvious traces. A case involving the assault of a police officer is examined to illustrate the use of the Principles: the problem originally defined by investigators at the scene and later by prosecutors resulted in incorrect analysis and interpretation of traces, hampering efforts at an accurate reconstruction of events. This exercise serves to demonstrate that in order to engage in scientific problem-solving, it is necessary to apply observation and reasoning in forensic investigations in order to yield an outcome that can be clearly articulated. The overarching goal is to support the drive to improve forensic science practice, education, and research through a case illustrating the value of the principles of the Sydney Declaration.     

Can latent fingerprint disclose the sex of the donor? A preliminary test study using GC–MS analysis of latent fingerprints

While fingerprints are a highly used means of identification, not every fingerprint left behind on a potential crime scene can be used for identification purposes. In some cases, the fingerprint may be smudged, partially preserved or overlapping with other prints hence distorting the ridge pattern and may therefore be not appropriate for identification. Further, fingermark residue yields a very low abundance of genetic material for DNA analysis. In such cases, the fingermark may be used to retrieve basic donor information such as sex. The focus of this paper was to assess the possibility of differentiating between the sexes of the donor of latent fingermarks. Analytical method was GC–MS analysis of the chemical compounds of latent fingermarks using 22 male and 22 female donors. Results showed 44 identified compounds. Two alcohols, octadecanol C₁₈ and eicosanol C₂₀, were found to show a difference that was statistically significant between male and female donors. There is also some evidence for the possibility of distinguishing sex of the fingermark donor based on the distribution of branched chain fatty acids, as free compounds or esterified in wax esters.     

Intentional overdose of glargine insulin: Determination of the parent compound in postmortem blood by LC-HRMS

Insulin glargine is a long-acting insulin analog that is converted after enzymatic cleavage of the arginine pair of the β-chain into its main metabolite M1 (21^A-Gly-insulin), which is responsible for the hypoglycemic activity. In all the overdose cases described in the literature, only M1 concentrations have been reported, whereas insulin glargine was always absent or below the limit of quantitation. In this study, we present a case of suicide of a young nurse by injection of insulin glargine in which the parent molecule was found at a toxic concentration in blood. The determination and the discrimination of insulin glargine from human insulin and other synthetic analogs in the blood specimen were performed by liquid chromatography coupled to high-resolution mass spectrometry (Waters XEVO G2-XS QToF) and extraction after precipitation in the presence of bovine insulin (internal standard), with a mixture of acetonitrile/methanol +1% formic acid followed by purification on solid phase extraction cartridges C18. Glargine insulin tested highly positive in the blood with a concentration of 1.06 mg/L. Due to the difficulty in obtaining a M1 pure standard, the metabolite could not be dosed. This unique presence of the parent molecule, reported for the first time, can be explained by inter-individual variability in the rate of conversion to metabolite. Intravenous injection versus subcutaneous injection can also explain the presence of insulin glargine. Finally, the dose injected may have been so high that saturation of the proteolytic enzymes responsible for conversion to M1 should have occurred.     

Radiodense bullet wipe around osseous entrance gunshot wounds

“Bullet wipe” is the material deposited by a bullet on any surface with which it comes into contact after it is fired and may contain debris from the gun barrel, including particles of primer and metal fragments from previously fired bullets. X‐ray analysis is a non‐destructive method by which traces of metallic elements can be visually detected. The analysis of osseous defects for radiodense bullet wipe (RBW) assists in determining the presence or absence of perforating gunshot wounds, especially in fragmented, skeletonized remains. The aim of our current study was to determine the frequency of RBW around entrance firearms injuries that perforated bone. We prospectively analyzed entrance gunshot wounds for RBW over a three‐year period using digital X‐ray analysis (n = 59). We retrospectively reviewed the corresponding autopsy reports to determine the frequency of RBW by biologic sex, reported ancestry, age‐at‐death, location of wound, manner of death, range of fire, bullet caliber, and presence of bullet jacket. Data were analyzed by Fisher's exact test or Chi‐square test with significance levels accepted at p < 0.05. RBW was present in 66% (n = 39) of examined cases. Decedent characteristics did not significantly alter RBW distribution, including biologic sex (p = 0.75), reported ancestry (p = 0.49), and age‐at‐death (p = 0.43). Additionally, the location of the osseous entrance gunshot wound, manner of death, range of fire, and cartridge caliber did not affect RBW detection. All cases involving non‐jacketed rounds (n = 5) showed RBW (p = 0.30). To our knowledge, this study is the first to report the frequency of RBW detection from osseous entrance gunshot wounds.     

Palynology and mycology as biological evidence in a homicide case

Criminal cases are studied from several disciplines to link a suspect with a criminal act. In this case, a man was reported missing in a coastal area in Buenos Aires Province, Argentina. The victim's relatives pointed to a possible suspect, and the local police carried out the investigation. We contributed to this research by applying palynological and mycological techniques. Palynomorphs and fungal spores offer valuable trace evidence, as they can be easily transferred between objects and crime scenes due to their minute size and persist on them for a long time. The victim was found 25 days later, lying on sandy soil, which partially covered the body, 35 km from where the suspect was arrested. Comparative samples were collected from the crime scene and the suspect's home and belongings (clothes, footwear, and seized vehicle). The palynological associations obtained from the crime scene and the defendant's belongings were dominated by diatoms and acritarchs (Acantomorphitae), all elements of marine origin, and a high CFU number of Bipolaris cynodontis, which allowed the defendant's clothing to be related to the place of corpse discovery. Soil from the defendant's home had an entirely continental composition, and the fungal biota was characteristic of prairie areas which were different from those of the crime scene.     

Standing for the client: on the interactional becoming of the criminal defence attorney1

In this essay, I explore the meaning of the legal profession (the defence attorney). I carry out my investigation in the interactional register. I suggest that we examine the profession of defence attorney as a professional identity in becoming. I localize the event of becoming in the first attorney-client interview. I propose that it is during the first encounter that the attorney comes to stand for the client as a legal counsel. I further propose that the analogy of ‘standing for’ be accessed empirically through an analysis of a recorded episode from the first attorney-client conference. For my methods I use a combination of frame analysis and conversation analysis. The two analyses show how the attorney becomes to stand for the client as a legal figure moulded in a series of interactional moves. By reformulating and reframing the ordinary talk that is introduced as an entry mode into an institutional relationship, the attorney and the client alter their discursive positions until the attorney assumes his professional identity, that is, becomes to stand for the client in legal action.