Solvent-free, Noncontact Electrostatic Sampling for Rapid Analysis with Mass Spectrometry: Application to Drugs and Explosives.

A hand-held Van de Graaf generator is used to apply a high voltage, negligible current electrostatic potential to a wire mesh positioned in close proximity to a particle-laden surface in order to collect those particles for analysis. The electrostatic field effects transfer particles to the mesh without a requirement for mechanical contact between mesh and surface. Analysis of chemicals present in the sampled particles is completed by thermal desorption electrospray ionization. The utility of the method for noncontact sampling is demonstrated using solid drug powder samples, and inorganic explosives dispersed either on solid surfaces or in sand/soil in order to simulate common interfering matrices that might be encountered in the forensic environment. A metal mesh sampling substrate is utilized instead of traditional polymer-based swabs in order to permit thermal desorption at higher temperatures. The method leaves no visible trace of sampling leaving details such as a fingerprint image unperturbed, as demonstrated using fluorescence photography. Direct sampling of trace particles from hard surfaces and skin documents flexibility in the choice of sampling substrates, desorption temperatures, and sampling times. The potential of the device for use in forensic analyses is detailed.

A cost-effectiveness analysis of the number of samples to collect and test from a sexual assault.

Although the backlog of untested sexual assault kits in the United States is starting to be addressed, many municipalities are opting for selective testing of samples within a kit, where only the most probative samples are tested. We use data from the San Francisco Police Department Criminalistics Laboratory, which tests all samples but also collects information on the samples flagged by sexual assault forensic examiners as most probative, to build a standard machine learning model that predicts (based on covariates gleaned from sexual assault kit questionnaires) which samples are most probative. This model is embedded within an optimization framework that selects which samples to test from each kit to maximize the Combined DNA Index System (CODIS) yield (i.e., the number of kits that generate at least one DNA profile for the criminal DNA database) subject to a budget constraint. Our analysis predicts that, relative to a policy that tests only the samples deemed probative by the sexual assault forensic examiners, the proposed policy increases the CODIS yield by 45.4% without increasing the cost. Full testing of all samples has a slightly lower cost-effectiveness than the selective policy based on forensic examiners, but more than doubles the yield. In over half of the sexual assaults, a sample was not collected during the forensic medical exam from the body location deemed most probative by the machine learning model. Our results suggest that electronic forensic records coupled with machine learning and optimization models could enhance the effectiveness of criminal investigations of sexual assaults.

Forgotten evidence: A mixed methods study of why sexual assault kits (SAKs) are not submitted for DNA forensic testing.

Throughout the United States, hundreds of thousands of sexual assault kits (SAKs) (also termed "rape kits") have not been submitted by the police for forensic DNA testing. DNA evidence can help sexual assault investigations and prosecutions by identifying offenders, revealing serial offenders through DNA matches across cases, and exonerating those who have been wrongly accused. In this article, we describe a 5-year action research project conducted with 1 city that had large numbers of untested SAKs-Detroit, Michigan-and our examination into why thousands of rape kits in this city were never submitted for forensic DNA testing. This mixed methods study combined ethnographic observations and qualitative interviews to identify stakeholders' perspectives as to why rape kits were not routinely submitted for testing. Then, we quantitatively examined whether these factors may have affected police practices regarding SAK testing, as evidenced by predictable changes in SAK submission rates over time. Chronic resource scarcity only partially explained why the organizations that serve rape victims-the police, crime lab, prosecution, and victim advocacy-could not test all rape kits, investigate all reported sexual assaults, and support all rape survivors. SAK submission rates significantly increased once criminal justice professionals in this city had full access to the FBI DNA forensic database Combined DNA Index System (CODIS), but even then, most SAKs were still not submitted for DNA testing. Building crime laboratories' capacities for DNA testing and training police on the utility of forensic evidence and best practices in sexual assault investigations can help remedy, and possibly prevent, the problem of untested rape kits. (PsycINFO Database Record

Rapid screening of synthetic cathinones as trace residues and in authentic seizures using a portable mass spectrometer equipped with desorption electrospray ionization.

RATIONALE: Recently, the surge in synthetic cathinone abuse has become a matter of public concern. With the influx of confiscated synthetic cathinones dramatically on the rise, laboratory workloads are expected to increase at a similar rate. This prompts the need for rapid analytical methods capable of detecting and identifying such compounds. METHODS: A ruggedized, portable ion trap mass spectrometer capable of desorption electrospray ionization mass spectrometry (DESI-MS) was used to rapidly characterize various synthetic cathinones. Target analytes were directly analyzed as trace residues on various substrates and as major components in authentic, powder-based forensic evidence. Physical transfer swabs can also be examined with this method, allowing efficient screening of large areas and geometrically complex samples. RESULTS: Method validity was tested on trace residues, mock forensic samples, and authentic evidentiary seizures, yielding low- to sub-ng detection limits from several substrates of interest to crime scene investigation. Analyte confirmation was accomplished through MS(2) analysis, providing characteristic fragmentation similar to that reported in literature. High-throughput analysis was demonstrated with no significant instrumental carryover, even for powdered samples. The robustness of this DESI-MS method to multi-component samples was examined, marked by high chemical specificity. CONCLUSIONS: Coupling DESI-MS with portable instrumentation allowed sensitive and selective examination of synthetic cathinones from various substrates, in complex mixtures, and directly from mock and authentic forensic evidence. This instrumental method has the potential to assess the evidentiary value of forensic samples at crime scenes, reducing backlogs and expediting criminal investigations.

Bodies of science and law: forensic DNA profiling, biological bodies, and biopower.

How is jurisdiction transferred from an individual's biological body to agents of power such as the police, public prosecutors, and the judiciary, and what happens to these biological bodies when transformed from private into public objects? These questions are examined by analysing bodies situated at the intersection of science and law. More specifically, the transformation of 'private bodies' into 'public bodies' is analysed by going into the details of forensic DNA profiling in the Dutch jurisdiction. It will be argued that various 'forensic genetic practices' enact different forensic genetic bodies'. These enacted forensic genetic bodies are connected with various infringements of civil rights, which become articulated in exploring these forensic genetic bodies''normative registers'.

Detection of drugs of abuse by Raman spectroscopy.

Raman spectroscopy can provide rapid, sensitive, non-destructive analysis of a variety of drug types (e.g. amphetamines, alkaloids, designer drugs, and date rape drugs). This review concentrates on developments in the past 15 years. It considers identification and quantification of drugs of abuse in different types of forensic evidence, including bulk street drugs as well as traces found in drinks, on fibres/clothing, in fingerprints, on fingernails, on bank notes, and in body fluids.

Helping with inquiries or helping with profits? The trials and tribulations of a technology of forensic reasoning.

The commercialization of forensic scientific provision in the UK over the last two decades has had a major role in shaping a changing epistemic identity for forensic scientists working within this jurisdiction. Efforts to match the presumed epistemological standards of the 'pure' sciences have been brought together with concerns about value for money in a new approach to the interpretation of evidence, an activity that lies at the heart of criminal investigative practice. A study of the Case Assessment and Interpretation method developed by members of the UK Forensic Science Service is used to show how a technical innovation in the delivery of forensic science services to the police has instantiated these two recent social processes.

Estimation of postmortem interval by hypoxanthine and potassium evaluation in vitreous humor with a sequential injection system.

The estimation of the time since death known as postmortem interval (PMI) is a main issue in the field of forensic science and legal medicine. In this work it is proposed a sequential injection system for the determination of hypoxanthine and potassium in the same sample of vitreous humor since the concentrations of both parameters change with PMI and the vitreous humor has been regarded as the ideal extracellular fluid for these kinds of determinations. By measuring both parameters the accuracy of estimation of PMI can be increased, and the effects of factors which influence the values in postmortem chemistry minimized. Hypoxanthine determination is based on its oxidation to uric acid (290 nm), catalyzed by immobilized xanthine oxidase, and the quantification of potassium levels in vitreous humor was performed using a tubular potassium ion-selective electrode. With a unique analytical cycle both analytes were evaluated being potassium levels determined during the degradation of hypoxanthine in the enzymatic reactor. Working concentration ranges between 6.04-40.00 micromol L(-1) and 7.00 x 10(-5) to 1.00 x 10(-1)mmol L(-1) were obtained, for hypoxanthine and potassium, respectively. The method proved to be reproducible with R.S.D. <5% for hypoxanthine and <3% for potassium. Sampling rate was approximately 30 per hour for the sequential determination of both parameters being 15 and 60 determinations per hour if hypoxanthine or potassium, where evaluated independently. Statistical evaluation at the 95% confidence level showed good agreement between the results obtained, for the vitreous humor samples, with both the SIA system and the comparison batch procedures. Moreover the methodology has low environmental impact in agreement with the demands of green analytical chemistry as only 2.7 mL of chemical waste is produced during both determinations.