Shedder status—An analysis over time and assessment of various contributing factors

The shedder status of a person is an important consideration when evaluating probabilities of DNA transfer during activity-level assessments. As an extension of our previously published study, the shedder statuses of 38 individuals were reassessed 1 year later. The study found that shedder status may change over time for some individuals and was associated with one's gender, number of items touched, and mobile phone usage. In 29% of touch events, no DNA allele was detected and in 99% of touch events, the amount of DNA deposited was <2 ng. The study also found that in 0.6% of touch events, the participant could be excluded as a contributor of the observed DNA profile, with another person being included. Additionally, our investigations suggest that the current three-category system for shedder status classification may require further refinement to better represent the individuals' shedder status in a population.     

Field-portable detection of fentanyl and its analogs: A review

The need to detect fentanyl and its analogs in the field is an important capability to help prevent unintentional exposure or overdose on these substances, which may result in death. Many portable methods historically used in the field by first responders and other field users to detect and identify other chemical substances, such as hazardous materials, have been applied to the detection and identification of these synthetic opioids. This paper describes field portable spectroscopic methods used for the detection and identification of fentanyl and its analogs. The methods described are automated colorimetric tests including lateral flow assays; vibrational spectroscopy (mid-infrared and Raman); gas chromatography–mass spectrometry; ion mobility spectrometry, and high-pressure mass spectrometry. In each case the background and key details of these technologies are outlined, followed by a discussion of the application of the technology in the field. Attention is paid to the analysis of complex mixtures and limits of detection, including the required spectral databases and algorithms used to interrogate these types of samples. There is also an emphasis on providing actionable information to the (likely) non-scientist operators of these instruments in the field.     

Rapid enantiomeric analysis of zopiclone in serum by supercritical fluid chromatography–tandem mass spectrometry

Zopiclone (ZOP) is a hypnotic drug prescribed to treat insomnia. Due to the chiral nature of ZOP, the psychologically active S-form and inactive R-form need to be determined enantiomerically in a forensic drug analysis. In the present study, a supercritical fluid chromatography (SFC) method was designed with a faster analysis ability than that of previously reported techniques. The SFC–tandem mass spectrometry (SFC–MS/MS) method was optimized using a column with a chiral polysaccharide stationary phase (Trefoil CEL2). ZOP was extracted from pooled human serum using solid-phase extraction (Oasis HLB) and analyzed. The developed SFC–MS/MS method achieved the baseline separation of S-ZOP and R-ZOP within 2 min. The fit-for-purpose method validation indicated that the optimized solid-phase extraction achieved near complete recovery and approximately 70% of the matrix effect. Both the retention time and peak area showed sufficient precision. The lower and upper limits of quantification (LOQ) were 5.7 × 10⁻² ng/mL and 25 ng/mL for R-ZOP, and 5.2 × 10⁻² ng/mL and 25 ng/mL for S-ZOP. The calibration line was linear in the range from lower LOQ to upper LOQ. The stability test indicated that ZOP in serum stored in a refrigerator (4°C) degraded and about 55% remained in 31 days. The quick analysis of the SFC–MS/MS method makes it a valid option for the enantiomeric analysis of ZOP.     

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.