Beware of the possibility of fingerprinting techniques transferring DNA

Fingerprinting brushes have the potential to collect and transfer DNA during powdering. Squirrel-hair fingerprint brushes exposed to specific sets of saliva stains and brushes used in routine casework were tested for their ability to collect and transfer DNA containing material using standard DNA extraction procedures and AmpFlSTR Profiler Plus amplification and typing procedures. The tests found that the risk of transferring DNA during powdering and having a detrimental impact on the analysis increases if the examiner powders over either biological stains (such as blood or saliva) or very fresh prints and uses more sensitive PCR amplification and typing procedures. We advocate caution when powdering prints from which DNA may also be collected and provide options for consideration to limit the risk of transferred DNA contamination while fingerprinting.     

Exclusion of a man charged with murder by DNA fingerprinting

DNA fingerprinting was used to demonstrate that two murder-rapes committed in 1983 and 1986, respectively, were connected. The probability of chance association of the fingerprint was calculated as 5.8 x 10(-8). The man who had been charged with the murder was excluded because his DNA fingerprint did not match sperm DNA fingerprints obtained from swabs and clothing attributed to the two victims.     

Assessment of disputed identity of blood alcohol samples using DNA fingerprinting

DNA fingerprinting is a perfect tool for investigating the identity of disputed blood by alcohol samples extracted. However, blood samples stored at an ambient temperature for longer periods can show considerable degradation of high-molecular DNA, diminishing the value of fingerprint investigation because of loss of the less frequent bands formed by the longer DNA fragments. Addition of the complexing agent EDTA can retard this degradation. Determination of the sex with DNA probes in the blood alcohol sample increases confidence in the investigation.     

Enhanced conditions for DNA fingerprinting with biotinylated M13 bacteriophage

Deoxyribonucleic acid (DNA) fingerprints are Southern blots which have a pattern resembling bar codes. The pattern is created by DNA probes that bind to variable-length repeated sequences of human genomic DNA digested with restriction endonucleases. To improve DNA fingerprints obtained with biotin-labeled M13mp8 replicative form (RF) bacteriophage as the gene probe, the conditions for hybridization and the subsequent washing steps of the filter were refined. Experiments were conducted varying the electrophoresis time, blotting membranes, hybridization solution, and posthybridization washes. The simplicity, sensitivity, and reliability of this nonistopic technique make possible its application for identification of individuals within a species, for parentage testing, and for monitoring bone marrow transplantation.     

The decision theory of paternity disputes: optimization considerations applied to multilocus DNA fingerprinting.

The solution of paternity disputes using results from scientific analyses is studied from a decision-theoretical viewpoint. Two alternative approaches to decision making, the so-called 'Bayes' and 'Minimax' strategies, are described and discussed. If prior probabilities of paternity are exactly known, then Bayes decisions are (a) independent of the source of evidence and (b) optimal with respect to average losses caused by wrong decisions. However, it is concluded that Minimax decisions, which depend upon the employed test system but not upon prior probabilities, are more appropriate in paternity cases if equal prior good will towards disclaimed children and alleged fathers is demanded. It is further demonstrated that, when major evidence about paternity comes from multilocus DNA fingerprinting, prior probabilities must be known quite accurately for Bayes decisions to be superior with respect to average losses. Finally, we are able to show that 'quasi' Bayes decision making, that is, adopting a neutral prior probability of 0.5 but leaving thresholds for decision making unchanged, coincides with Minimax decision making if multilocus DNA fingerprinting is employed.     

Ballistic fingerprinting databases

This article discusses a number of questions regarding the setting up of ballistic fingerprinting databases, consisting of ammunition components fired by all the firearms held in legal possession. These questions can be classified into three categories--the efficiency of the database, forensic issues, and practical issues to be dealt with. The current New York State legislation is used as an illustration of the choices to be made when setting up a ballistic fingerprinting database. Three important arguments are formulated against the installation of a ballistic fingerprinting database.     

Evaluation of a semi-automated, magnetic bead-based DNA extraction method for genetic fingerprinting of forensic casework samples

In order to cope with the demanding workload for DNA profiling of forensic casework samples a concept for a semi-automated processing system was developed at the Landeskriminalamt (Office of Criminal Investigation) Baden-Württemberg, Germany [K. Vollack, et al., Implementation of a semi-automated processing system for DNA profiling of forensic casework samples, this issue]. The applied magnetic bead extraction method is based on ChargeSwitch^® Technology (CST) from Invitrogen and was established on a liquid handling workstation Freedom EVO^® 150 from Tecan.     

Demonstration of a gastric bioptic specimen mix-up by laser capture microdissection (LCM) and DNA fingerprinting

We demonstrate here the successful use of laser capture microdissection (LCM) and DNA fingerprinting in the identification of a case of gastric bioptic specimen mix-up. A 70-year-old man, suffering from chronic atrophic gastritis, underwent to a gastric biopsy and received a diagnosis of gastric cancer. In the absence of any clinical evidence of gastric cancer, a specimen mix-up was suspected. LCM was used to retrieve gastric cells from the histologic slide, classified as gastric carcinoma, and suspected to be mislabelled. DNA was extracted from microdissected cells, and a total of 16 different genetic loci were analyzed, using an identity test. Comparison of the results with those obtained using DNA extracted from a control slide, and from patient's saliva, demonstrated a distinct DNA fingerprint pattern in all genetic markers examined, clearly indicating the occurrence of a specimen mix-up. The combined use of LCM and DNA fingerprinting represents the most accurate and sophisticated method available for the identification of specimen mix-up, especially when only the tissue on the suspected slide is available.     

Impersonator identification through dynamic fingerprinting

Tracking the source of impersonation attacks is a difficult challenge for investigators. The attacks are frequently launched from botnets comprised of infected, innocent users and web servers compromised by malware. Current investigative techniques focus on tracking these components. In this paper, we propose the Automated Impersonator Image Identification System (AIIIS), which allows investigators to track images used in impersonation attacks back to the original download from the source. AIIIS accomplishes this by digitally encoding the IP address, server, and time of the image download into the image itself through a digital watermark. AIIIS differs from other image fingerprinting techniques in its combination of dynamic fingerprinting and spread spectrum data hiding. Additionally, the intended goal of AIIIS is tracking impersonation attacks, where the image is a tool used, whereas in most digital rights management techniques, the misuse of the content itself is the primary concern. Our experiments show that the AIIIS system permits recovery even after post-acquisition manipulation of the image, making it a significant addition to the fight against impersonators. The deployment of a pilot of AIIIS was successful in identifying the source of an impersonation attack, and further success is expected with full deployment.     

Chemical fingerprinting of unevaporated automotive gasoline samples

The comparison of two or more samples of liquid gasoline (petrol) to establish a common origin is a difficult problem in the forensic investigation of arsons and suspicious fires. A total of 35 randomly collected samples of unevaporated gasoline, covering three different grades (regular unleaded, premium unleaded and lead replacement), were examined. The high-boiling fraction of the gasoline was targeted with a view to apply the techniques described herein to evaporated gasoline samples in the future.A novel micro solid phase extraction (SPE) technique using activated alumina was developed to isolate the polar compounds and the polycyclic aromatic hydrocarbons (PAHs) from a 200microl sample of gasoline. Samples were analysed using full-scan gas chromatography-mass spectrometry (GC-MS) and potential target compounds identified. Samples were then re-analysed directly, without prior treatment, using GC-MS in selected ion monitoring (SIM) mode for target compounds that exhibited variation between gasoline samples. Principal component analysis (PCA) was applied to the chromatographic data. The first two principal components (PCs) accounted for 91.5% of the variation in the data. Linear discriminant analysis (LDA) performed on the PCA results showed that the 35 samples tested could be classified into 32 different groups.     

A technique to enhance fingerprinting of mummified fingers

This report details a fingerprinting technique for softening mummified fingers and hands using Metaflow and Restorative, a fluid for rehydration of desiccated tissue. This procedure has proven successful in cases of extreme desiccation and has allowed for good fingerprint detail to be developed.     

微生物物证检验的核酸分析技术

本文阐述了核酸分析技术中的VNTR／MLVA、PFGE、AFLP、SNP等方法和这些方法在生物犯罪中的实际应用；对这些方法的特点进行了总结归纳，并提出了我国公安机关在当前形势下发展核酸分析技术的一些建议。     

A novel approach for fingerprinting mummified hands

Abstract:  Fingerprinting has long been used as a method for identifying bodies and, since first discovered, many advances have been made in both fingerprint acquisition and interpretation. However, in the field of forensic pathology, the attainment of fingerprints from mummified bodies has remained difficult. The most common technique historically used to obtain fingerprints in these cases usually employs the amputation of the fingers combined with soaking and/or injecting the fingers with various solutions in order to enhance the fingerprints. A novel approach to fingerprinting mummified fingers is presented which involves removal and rehydration of the fingerpads (including the epidermal, dermal, and adipose tissues) followed by inking and rolling, using a gloved finger for support. The technique presented produces a superior quality of print without amputation of the finger, yielding excellent results and assisting in obtaining positive identification.     

Analysis of the possible use of liquid crystals in fingerprinting

Preliminary results concerning the use of liquid crystals (LC) in fingerprinting are given. These were based on thin layers of liquid crystals, changing colours (observed in linear polarized light) due to dissolved organic matter, transferred from fingers' surfaces. The possibility is shown of using LC to illustrate not only the surface but also the spacial configuration of a fingerprint. Relations are given between the amount of organic matter generating a fingerprint on a given surface and the coloured "response" of LC which may be used for identification as well as approximate estimation of the process of ageing.     

Identification of blood stains and fetal tissue using genetic fingerprinting

Two cases from practical forensic serological investigations which could not be clarified by means of conventional serological methods, but could be resolved on the basis of the DNA finger print technique with oligonucleotide probes are presented. Both the comparison of the identity of the blood sample which had been stored for a long time and the determination of paternity in fetal material in a case of incest demonstrate the enormous possibilities of this method. However, some problems which still have not been resolved at least at present with regard to the evaluation and appraisal of the band patterns are also discussed.     

Chemical fingerprinting of adhesive tapes by GCMS detection of petroleum hydrocarbon products

Pressure-sensitive adhesive tapes often represent key evidence of crimes such as assault, rape or homicide; thus, the development of analytical techniques able to contribute to a detailed characterization of these materials is of forensic importance. The gas chromatography-mass spectrometry (GCMS) analysis of the solvent extractable fractions of a suite of electrical and gaffer adhesive tapes spanning a range of colors and manufacturers identified a number of petroleum-derived hydrocarbons. Molecular and isotopic analyses of hydrocarbon constituents of complex materials have found wide analytical utility including the forensic investigation of oil spills and arson. Here, we investigate the utility of these techniques for characterizing the hydrocarbon composition of pressure-sensitive adhesive tapes for forensic correlation purposes. Subtle distinction of tape samples was evident in the GCMS distribution of several hydrocarbon groups including alkyl-naphthalenes, hopane and sterane biomarkers. Linear discriminant analysis of the abundances of these products provided high level differentiation of tape manufacturer. The distinction of different adhesive tape samples was further extended by measurement of their stable carbon isotopic values. The molecular and isotopic differences of the petroleum content of tapes are consistent with the use of different petroleum materials used in the manufacturing process and demonstrate the benefits of the combined use of complementary oil hydrocarbon characterization approaches. This study reveals the forensic potential of using established petroleum characterization methods for characterizing materials with a petroleum-derived hydrocarbon element.     

A rapid gas chromatographic method for the fingerprinting of illicit cocaine samples.

A gas chromatographic (GC) fingerprint method, based on the presence or absence of six congeners, was developed for illicit cocaine samples. The fingerprint utilizes the relative abundances of these congeners towards each other, disregarding cocaine as the main constituent, and can be expressed numerically or graphically in the form of pictograms for rapid visual comparison. The method can be applied directly to a solution of the sample in chloroform, without previous workup procedures. More than 70 unrelated samples were analyzed and a great variation was observed in the parameter composition. On the other hand, a remarkable similarity could be seen between related samples. The GC fingerprint method may be considered an important contribution for sample comparison, as is exemplified by a subdivision of the analyzed samples in different categories, based on the number and types of congeners found.     

Rapid presumptive "fingerprinting" of body fluids and materials by ATR FT-IR spectroscopy

Human body fluids and materials were evaluated using attenuated total reflectance Fourier transform infrared spectroscopy. Purified proteins, cosmetics, and foodstuffs were also assayed with the method. The results of this study show that the sampled fluids and materials vary in the fingerprint region and locations of the amide I peaks because of the secondary structure of the composite proteins although the C = O stretch is always present. The distinct 1016 cm(-1) peak serves as a signature for semen. The lipid-containing materials (e.g., fingerprints, earwax, tears, and skin) can also be easily separated from the aqueous materials because of the strong CH(3) asymmetric stretch of the former. Blood-saliva and blood-urine mixtures were also successfully differentiated using combinations of peaks. Crime scene investigators employing rapid, portable, or handheld infrared spectroscopic instruments may be able to reduce their need for invasive, destructive, and consumptive presumptive test reagents in evaluating trace evidence.