Secondary transfer of organic gunshot residues: Empirical data to assist the evaluation of three scenarios

The present study aimed at providing data to assess the secondary transfer of organic gunshot residues (OGSR). Three scenarios were evaluated in controlled conditions, namely displacing a firearm from point A to point B, a simple handshake and an arrest involving handcuffing on the ground. Specimens were collected from the firearm, the hands of the shooter and the non-shooter undergoing the secondary transfer in order to compare the amounts detected.Secondary transfer was observed for the three scenarios, but to a different extent. It was found that displacing a firearm resulted in secondary transfer in <50% of the experiments. The firearm also had an influence, as contrary to the pistol, no secondary OGSR were detected using the revolver. Shaking the hand of the shooter also transferred OGSR to the non-shooter's hand. In that case, the amount of OGSR was generally higher on the shooter than on the non-shooter. Finally, the largest secondary transfer was observed after the arrest with handcuffing with positive results in all cases using the pistol. In that scenario, the amounts on the shooter and the non-shooter were in the same range.This study highlights that the secondary transfer must be taken into account in the interpretation of OGSR. Indeed, an individual's hands might be contaminated by handling a firearm or having physical contact with a shooter.     

英国警察武器使用概览

英国警察使用武器经历了一个渐进的备受争议的发展过程,大多数警察对武装化持抵制态度。目前,英国警方通过培训授权持枪警察、装备武装反应警车来处置需要使用武器的紧急事件,不同警种使用的武器也有差异。警察开枪事件常常引发公众的非议。     

Trends in Converted Firearms in England & Wales as Identified by the National Firearms Forensic Intelligence Database (NFFID) Between September 2003 and September 2008

Abstract: The National Firearms Forensic Intelligence Database (NFFID © Crown Copyright 2003‐2008) was developed by The Forensic Science Service (FSS) as an investigative tool for collating and comparing information from items submitted to the FSS to provide intelligence reports for the police and relevant government agencies. The purpose of these intelligence reports was to highlight current firearm and ammunition trends and their distribution within the country. This study reviews all the trends that have been highlighted by NFFID between September 2003 and September 2008. A total of 8887 guns of all types have been submitted to the FSS over the last 5 years, where an average of 21% of annual submissions are converted weapons. The makes, models, and modes of conversion of these weapons are described in detail. The number of trends identified by NFFID shows that this has been a valuable tool in the analysis of firearms‐related crime.     

Ten methods for calculating the uncertainty of measurement

While forensic laboratories are coming under increasing pressure to provide meaningful estimates of measurement uncertainty, there has been little discussion of this topic in the literature. This article summarizes ten bases for estimating this parameter: (1) proficiency tests; (2) readability limits; (3) independent reference materials; (4) operational limits applied during calibration; (5) expert judgment; (6) precision control samples without (6) and with (7) contributions from extramural sources of error; (8) error budgets; (9) historical performance; and (10) ruggedness tests. Based on the assumptions underlying each approach, the forensic community will need to apply a variety of discipline-specific approaches to arrive at satisfactory estimates of measurement uncertainty.     

Visualisation by confocal microscopy of traces on bullets and cartridge cases

The capabilities of confocal scanning laser microscopy for the visualisation of marks on bullets and cartridge cases were investigated. Confocal microscopy provides solutions to important limitations of conventional comparison microscopy with grazing light incidence, as generally used for the examination of these marks. It is expected that confocal microscopy, thanks to its broad applicability within the field of firearms investigation and its capability of non-destructively gathering quantitative three-dimensional information, will lead to a more complete and objective forensic examination of bullets and cartridge cases.     

Unusual sources of Sn in GSR. An experimental study by SEM and IBA

Gunshot Residue (GSR) produced by the discharge of a firearm often provides very useful information in criminal investigations in cases involving the use of firearms. Scanning Electron Microscopy equipped with an Energy Dispersive X-ray Spectrometer (SEM-EDS) is typically used worldwide to visualize micrometric particles constituting GSR and to analyse their elemental composition. The 2017 ASTM Standard guide for gunshot residue analysis by scanning electron microscopy/energy dispersive X-ray spectroscopy specifies that “Particles classified as characteristic of GSR will have one of the following elemental compositions: Lead, antimony, barium; Lead, barium, calcium, silicon, tin”. For the first time, the presence of an additional element, such as Sn, plays a key role in ASTM particle classification. It is known that some ammunitions, used for pistols, revolvers and rifles, contain tin foil discs for sealing the primer mixture into the cup, resulting in GSR particles containing Sn. The authors faced some cases in which Sn was unexpectedly found in GSR particles from a 0.22 Long Rifle derringer and from some 12 gauge shotguns. No tin foil discs are used in rimfire ammunitions and there is no published evidence of tin foil discs in shotshell ammunitions. Following a “case by case” approach, experimental research has been carried out to explain how Sn can be present in GSR particles when the last discharged cartridge also does not contain any Sn either in components and in the explosive charges.Moreover, the use of Particle Induced X-ray Emission (PIXE) showed the capability to overcome overlap ambiguity of Sb and Sn peaks in the X-ray spectra, being a possible key issue in real shooting cases if Sn quantities are below the lower limit of SEM detection, especially when Sb is also present.     

香港警察枪械使用法律制度述评简

我国香港《警察通例》及《警察程序手册》对警察使用枪械的原则、条件、程序等内容作了具体、全面、细致的规定。其特点是：立足自身实际进行制度设计，对警察使用枪械予以全程规制，程序严格，注重警察用枪安全。香港警察枪械使用法律制度的优点值得内地在完善相关立法时加以借鉴。     

Reference ballistic imaging database performance

Ballistic imaging databases allow law enforcement to link recovered cartridge cases to other crime scenes and to firearms. The success of these databases has led many to propose that all firearms in circulation be entered into a reference ballistic image database (RBID). To assess the performance of an RBID, we fired 4200 cartridge cases from 600 9 mm Para Sig Sauer model P226 series pistols. Each pistol fired two Remington cartridges, one of which was imaged in the RBID, and five additional cartridges, consisting of Federal, Speer, Winchester, Wolf, and CCI brands. Randomly selected samples from the second series of Remington cartridge cases and from the five additional brands were then correlated against the RBID. Of the 32 cartridges of the same make correlated against the RBID, 72% ranked in the top 10 positions. Likewise, of the 160 cartridges of the five different brands correlated against the database, 21% ranked in the top 10 positions. Generally, the ranking position increased as the size of the RBID increased. We obtained similar results when we expanded the RBID to include firearms with the same class characteristics for breech face marks, firing pin impressions, and extractor marks. The results of our six queries against the RBID indicate that a reference ballistics image database of new guns is currently fraught with too many difficulties to be an effective and efficient law enforcement tool.     

日本警察枪支使用法律制度及其借鉴意义

日本立法对警察使用枪支予以全程规制,规定了事先拔枪、准备射击、开枪时预告、开枪恐吓、开枪射击和报告等内容,对使用枪支的不同形态分别设定条件,并以高阶位法设定警察开枪的条件,规定内容详尽,使用枪支条件的设定比较合理。对于日本警察枪支使用法律制度的这些优点,我国在完善自身相关法律制度的过程中可以借鉴。