Bloodstain classification methods: A critical review and a look to the future.

Classifying bloodstains is an essential part of Bloodstain Pattern Analysis. Various experts have developed methods. Each method considers the same basic bloodstain pattern types. These use either terminology based on the observable characteristics or the mechanistic cause of the bloodstain patterns as part of the classification process. This review paper considers ten classification methods from fourteen sources, which are used to classify bloodstain patterns. There are fundamental differences in how the patterns are classified, how differentiated the classification is, and whether the classification process uses clear, unambiguous criteria, and is susceptible to contextual bias. Experts have also reported issues with classifying bloodstains that have indistinguishable features. These differences expose key limitations with current classification methods: mechanistic terminology is too heavily relied on, and the classification process is susceptible to contextual bias. The development of an unambiguous classification method, based on directly observable characteristics within bloodstain patterns is recommended for future work.

An evaluation of two adhesive media for the recovery of DNA from latent fingermarks: A preliminary study.

Dual recovery of forensic evidence is beneficial for crime scene and evidence processing as it can potentially double the evidential value of a single source, even more so in instances of DNA fingermarks. The use of adhesive liftering media has shown comparable results to swabbing when dealing with trace DNA recovery. Gelatine lifters have displayed the potential to recover DNA from latent fingermarks with minimal alteration to friction ridge detail post application, yet their ability to recover DNA has not fully been explored. The aim of this research was to compare the use of gelatine lifters with more readily available masking tape in their ability to recover cellular material from latent fingermarks. Natural (n = 120) and sebaceous (n = 120) fingermarks were deposited and aged in time frames from fresh, 1-day, 2-day, 1-week, 2-weeks, and 1 month. DiamondTM Nucleic Acid Dye was used as a visualisation method for any DNA containing cellular material. Images of the fingermarks pre and post lifting, and on the lifting media were imaged using the DSC®5 system. The media's ability to recover cellular material was assessed using fluorescent particle analysis by the employment of the free software ImageJ. Fluorescent particles could be observed on the lifting media post lifting with the use of DiamondTM Dye. Time was not seen to influence the variation in the number of fluorescent particles observed. The use of gelatine lifters was found to have a higher amount of recovered DNA containing cellular material than masking tape. Visualisation of particles on masking tape were inhibited by its porosity and absorption of the dye. Some fingermark detail could be observed in the gelatine lifters. The DSC®5 system was suitable for imaging fingermarks stained with DiamondTM Dye.

Collaborative practise in forensic science and academia: The development of a documentation strategy for fingerprint examinations in an English fingerprint bureau in the ISO 17025 era.

The mandatory introduction of ISO 17,025 accreditation to fingerprint comparisons forced changes to the documentation procedures. Academic and grey literature consistently suggest that the documentation should provide a sufficient auditable trail, yet there is some dissimilarity in the guidance relating to documentation content, and subjectivity with its interpretation. The accreditation body, UK Accreditation Service (UKAS), was not prescriptive in the methods required to produce working notes and were open to different practises, which has provided a useful opportunity to compare approaches to casework and to work with practitioners to inform effective practise. The research team carried out a gap analysis between pre-accreditation operational documentation practise and an ACE-V checklist, which was a summary of best practise guidance on documentation content. A white box study included thirty-one fingerprint examiners from six institutions, who were asked to undertake an 'Analysis' of eight friction ridge impressions. Participants were asked to produce working notes using their pre-accreditation documentation approach and a piece of software called 'PiAnoS', which prompted mark annotation and an assessment of mark quality. The notes were compared to the ACE-V checklist to determine which of the documentary suggestions were considered to obtain an understanding of experts' decision making. The results were used to develop a documentation strategy for an operational English fingerprint bureau, referred to as a "Mark Analysis Form". It consisted of content from the ACE-V checklist, supported by literature, and which received high response rates from experts alongside discussions by the research team to determine its relevance in the documentation strategy. The strategy met with the ISO 17,025 standard, evidenced by UKAS approval, and is currently used for casework.

The adaptation of a 360° camera utilising an alternate light source (ALS) for the detection of biological fluids at crime scenes.

One of the most important and commonly encountered evidence types that can be recovered at crime scenes are biological fluids. Due to the ephemeral nature of biological fluids and the valuable DNA that they can contain, it is fundamental that these are documented extensively and recovered rapidly. Locating and identifying biological fluids can prove a challenging task but can aid in reconstructing a sequence of events. Alternate light sources (ALS) offer powerful non-invasive methods for locating and enhancing biological fluids utilising different wavelengths of light. Current methods for locating biological fluids using ALS's may be time consuming, as they often require close range searching of potentially large crime scenes. Subsequent documentation using digital cameras and alternate light sources can increase the investigation time and due to the cameras low dynamic range, photographs can appear under or over exposed. This study presents a technique, which allows the simultaneous detection and visualisation of semen and saliva utilising a SceneCam 360° camera (Spheron VR AG), which was adapted to integrate a blue Crime Lite XL (Foster+Freeman). This technique was investigated using different volumes of semen and saliva, on porous and non-porous substrates, and the ability to detect these at incremental distances from the substrate. Substrate type and colour had a significant effect on the detection of the biological fluid, with limited fluid detection on darker substrates. The unique real-time High Dynamic range (HDR) ability of the SceneCam significantly enhanced the detection of biological fluids where background fluorescence masked target fluorescence. These preliminary results are presented as a proof of concept for combining 360° photography using HDR and an ALS for the detection of biological stains, within a scene, in real time, whilst conveying spatial relationships of staining to other evidence. This technique presents the opportunity to presumptively screen a crime scene for biological fluids and will facilitate simultaneous location and visualisation of biological evidence.

A comparative study of photogrammetric methods using panoramic photography in a forensic context.

Taking measurements of a scene is an integral aspect of the crime scene documentation process, and accepted limits of accuracy for taking measurements at a crime scene vary throughout the world. In the UK, there is no published accepted limit of accuracy, whereas the United States has an accepted limit of accuracy of 0.25 inch. As part of the International organisation for Standardisation 17020 accreditation competency testing is required for all work conducted at the crime scene. As part of this, all measuring devices need to be calibrated within known tolerances in order to meet the required standard, and measurements will be required to have a clearly defined limit of accuracy. This investigation sought to compare measurement capabilities of two different methods for measuring crime scenes; using a tape measure, and a 360° camera with complimentary photogrammetry software application. Participants measured ten fixed and non-fixed items using both methods and these were compared to control measurements taken using a laser distance measure. Statistical analysis using a Wilcoxon Signed Rank test demonstrated statistically significant differences between the tape, software and control measurements. The majority of the differences were negligible, amounting to millimetre differences. The tape measure was found to be more accurate than the software application, which offered greater precision. Measurement errors were attributed to human error in understanding the operation of the software, suggesting that training be given before using the software to take measurements. Transcription errors were present with the tape measure approach. Measurements taken using the photogrammetry software were more reproducible than the tape measure approach, and offered flexibility with regards to the time and location of the documentation process, unlike manual tape measuring.

The effect of DNA recovery on the subsequent quality of latent fingermarks.

The recovery of DNA and fingermark evidence from the same site can be problematic on account of potential contamination from fingermark visualisation techniques, and/or the destructive capability of the DNA recovery method. Forensic investigators are therefore often required to choose which evidence type to recover, or to recover both evidence types from different sites. Research typically documents the effects of fingermark visualisation techniques on the subsequent recovery of DNA, whereas this research has investigated the effects of DNA recovery on the quality of subsequently recovered latent fingermarks. Eccrine rich, sebaceous rich, and 'normal' latent fingermarks were deposited onto five substrates: glass; aluminium; textured plastic; varnished wood; photocopier paper and aged from 4h to 4 weeks. Approximately half of the control fingermarks were developed without DNA recovery on all substrates. The remaining samples were subjected to one of five DNA recovery methods prior to fingermark development. Pre and post DNA recovered fingermarks were graded for quality, and AFIS correlations scores were obtained and analysed for statistically significant differences using Wilcoxon Signed Rank tests and Friedman tests. All of the DNA recovery methods reduced the quality of latent fingermarks on glass surfaces. Flocked swabs and gel lifts were the least destructive DNA recovery methods on the remaining surfaces, except for aluminium sheet metal. The quality of latent fingermarks deposited onto glossed wood and textured plastic and paper were less affected by dry swabbing. Wet swabbing and tape lifting were very damaging methods of DNA recovery.

The design and implementation of a proficiency test for assessors of fingermark quality, to facilitate collaborative practise in fingermark research.

Significant numbers of institutions are carrying out fingermark based research, yet there appears to be little inter-institution consistency in the approaches used to assess the quality of the samples produced. Inter-institution consistency in quality assessment would lead to inevitable benefits in collaborating research projects, given that data from multiple projects may be combined, or compared. In order for such quality assessment schemes to be effectively used across multiple institutions, proficiency in using such approaches should be identified to ensure parity. Intra-institution controls on fingermark quality assessment are likely to help manage variations between researchers from the same institution and/or project(s). Proficiency testing (PT) is a popular means of comparing and monitoring the competency of individuals, whilst also assessing the validity of data and conclusions. This project aimed to develop a proficiency testing scheme for the assessment of fingermark quality for researchers. A grading system was developed to assess the quality of fingermarks generated within research projects. A large collection of test fingermark samples was created controlling variables such as force, fingermark composition and surface type. An 'inter-laboratory testing scheme' design was used for the proficiency test and established fingermark researchers participated in the project to produce known values for 6 chosen test samples for round one of the testing scheme, described in this paper. Second year BSc (Hons) Forensic Science and Forensic Investigation student participants from the host institution completed the proficiency test as part of a fingermark practical. Results indicated that student participants involved in this project were not able to demonstrate a satisfactory level of proficiency of fingermark quality assessment using this grading system, which was attributed to their relative experience in assessing the quality of fingermarks compared to 'experts' in fingermark analysis. Results have highlighted considerations for future grading systems, and additional training requirements of users.

An investigation into the effects of force applied during deposition on latent fingermarks and inked fingerprints using a variable force fingerprint sampler.

Physical factors, including the magnitude of the force applied during fingermark deposition, may affect friction ridge surface area and clarity, and the quantity of residue transferred. Consistency between fingermarks may be required; for example, in research projects, yet differences between marks are likely to exist when physical factors are not controlled. Inked fingerprints and latent fingermarks were deposited at 1-10 N at 1 N increments using a variable force fingerprint sampler to control the force, angle of friction ridge and surface contact, and the duration of friction ridge and surface contact. Statistically significant differences existed between the length and width measurements of the inked prints (p ≤ 0.05), particularly at lower forces. Scanning electron microscopy and surface plot analysis demonstrated how differences in force applied during deposition affected ridge surface area, displacement of latent residue, and differences in the quantity of residue transferred. Consistency between inked prints was demonstrated at equivalent forces.

An investigation into the use of a portable cyanoacrylate fuming system (SUPERfume®) and aluminum powder for the development of latent fingermarks.

Few techniques offer "in situ" methods of friction ridge skin mark development. "In situ" development reduces mark transportation, degradation, and often cost. The effectiveness of cyanoacrylate fuming using the SUPERfume(®) and dusting with aluminum powder for latent fingermark development on several nonporous surfaces, stored in various temperature environments for time periods up to 52 weeks, was investigated. Five thousand and four hundred latent fingermarks were deposited under controlled conditions and graded. The results suggested that cyanoacrylate fuming (SUPERfume(®), Foster and Freeman, U.K.) was more effective at developing latent fingermarks on textured and smooth plastic surfaces and for marks stored in temperatures of 37 °C, whereas aluminum powder was more effective on glass, enameled metal paint, and varnished wood, and for storage temperatures below 20 °C. There were no significant benefits to using either technique for marks older than 24 h, but it was possible to develop fingermarks following 52 weeks of storage using both techniques.

Consistency and reproducibility in fingermark deposition.

A review of the available literature and previous research has suggested that there are several factors associated with the deposition of friction ridge skin marks that can affect the quality of the resultant marks, including the quantity of force applied, the angle of friction ridge and surface contact and the duration of friction ridge and surface contact. A device referred to as a fingerprint sampler was designed and constructed to facilitate the deposition of fingermarks for research projects. Fingermarks were deposited with and without the fingerprint sampler and examined for evidence of distortion. The quality of the marks was also assessed. The results of this study suggested that the fingerprint sampler deposited fingermarks without distortion caused by some physical factors associated with deposition and that the marks were of a statistically significantly higher quality than marks deposited without its use.

Determination of the sequence of latent fingermarks and writing or printing on white office paper.

Latent fingermarks were deposited onto white office paper samples containing writing or printing from several media (for example, ballpoint pens and laser printers). Fingermarks were deposited both before and after writing/printing. The marks were then treated with appropriate latent fingermark development techniques. Once treated, they were examined with standard techniques applied in document examination (filtered light analysis, electrostatic detection device and Raman spectroscopy) to determine the sequence of application. The results suggested that the sequence of laser printing and latent marks could be determined via electrostatic detection device examination of undeveloped and Ninhydrin developed samples.