Gamma Irradiation as a Biological Decontaminant and Its Effect on Common Fingermark Detection Techniques and DNA Profiling

Abstract:  The use of disease-causing organisms and their toxins against the civilian population has defined bioterrorism and opened forensic science up to the challenges of processing contaminated evidence. This study sought to determine the use of gamma irradiation as an effective biological decontaminant and its effect on the recovery of latent fingermarks from both porous and nonporous items. Test items were contaminated with viable spores marked with latent prints and then decontaminated using a cobalt 60 gamma irradiator. Fingermark detection was the focus with standard methods including 1,2-indanedione, ninhydrin, diazafluoren-9-one, and physical developer used during this study. DNA recovery using 20% Chelex extraction and quantitative real-time polymerase chain reaction was also explored. Gamma irradiation proved effective as a bacterial decontaminant with D -values ranging from 458 to 500 Gy for nonporous items and 797–808 Gy for porous ones. The results demonstrated the successful recovery of latent marks and DNA establishing gamma irradiation as a viable decontamination option.     

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

Abstract: 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.     

Use of styryl 11 and STaR 11 for the luminescence enhancement of cyanoacrylate-developed fingermarks in the visible and near-infrared regions

In current casework, most post-cyanoacrylate stains rely on luminescence emission in the visible region (400-700 nm). While traditional stains such as rhodamine 6G work well under most circumstances, some surfaces may generate background luminescence under the same conditions. Detection in the near-infrared region (NIR > 700 nm) has shown to be effective in minimizing the interferences from such surfaces. The laser dye styryl 11 generated strongly luminescent fingermarks when applied after cyanoacrylate fuming on all surfaces tested. When compared to rhodamine 6G, the dye was superior only when viewed in the NIR. Styryl 11 was subsequently combined with rhodamine 6G, and the mixed stain formulation (named StaR 11 by the authors) induced stronger luminescence compared with styryl 11 alone with an ability to visualize in both the visible and NIR regions. Reliable and consistent results were obtained when using either styryl 11 alone or the STaR 11 mixture. The enhancement achieved did not otherwise vary depending on the source of the fingermark secretions. With visualization possible in both the visible and NIR regions, the styryl 11/rhodamine 6G mixture showed significant potential as a post-cyanoacrylate stain.     

The Development and Evaluation of Radiological Decontamination Procedures for Documents,Document Inks,and Latent Fingermarks on Porous Surfaces*†

Abstract: Criminal acts such as an attack utilizing a radiological dispersal device (RDD or dirty bomb), the manufacture of such a device, or the illicit trafficking of radioactive materials would warrant a criminal investigation. This could involve the collection, transportation, and analysis of radiologically contaminated trace evidence. But are law enforcement agencies and forensic scientists capable of dealing with this? This research investigates the decontamination efficacy of two decontamination techniques (chemical and physical) designed for the removal of radiological material from documents of forensic importance. The impact that these procedures have on the development of latent fingermarks and the forensic analysis of the inks on these documents is also studied. It was found that slight changes in the color and chemical composition of a variety of document inks and a destruction of fingermark ridges occurred after chemical decontamination. Physical decontamination had no impact on these parameters.     

Laser desorption/ionization time-of-flight mass spectrometry of triacylglycerols and other components in fingermark samples

The chemical composition of fingermarks could potentially be important for determining investigative leads, placing individuals at the time of a crime, and has applications as biomarkers of disease. Fingermark samples containing triacylglycerols (TAGs) and other components were analyzed using laser desorption/ionization (LDI) time-of-flight mass spectrometry (TOF MS). Only LDI appeared to be useful for this application while conventional matrix-assisted LDI-TOF MS was not. Tandem MS was used to identify/confirm selected TAGs. A limited gender comparison, based on a simple t-distribution and peaks intensities, indicated that two TAGs showed gender specificity at the 95% confidence level and two others at 97.5% confidence. Because gender-related TAGs differences were most often close to the standard deviation of the measurements, the majority of the TAGs showed no gender specificity. Thus, LDI-TOF MS is not a reliable indicator of gender based on fingermark analysis. Cosmetic ingredients present in some samples were identified.     

Revisiting the Thermal Development of Latent Fingerprints on Porous Surfaces: New Aspects and Refinements*

Abstract: Although the ability to develop latent fingerprints on paper using heat alone has been noted previously, it has been considered impractical for casework and inferior to other techniques. Here a new refinement of the technique is demonstrated for the high quality development of latent fingerprints on porous surfaces such as paper. Fingerprints deposited on various papers were developed by exposing them to hot air with a temperature in the vicinity of 300°C, for periods of c. 10–20 sec. Several different heating methods were tested. The novel observation was made that after shorter heating times, fluorescent prints could be observed. These became visible after longer heating times, as noted by earlier workers, but with greatly improved contrast compared with their results. Prints from various donors (and aged prints) were developed with excellent ridge contrast. Direct heating methods (such as with a hot plate or press) produced inferior results. The refined technique, which is simple, safe and inexpensive compared with conventional methods, has great potential for use in forensic laboratories.