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.     

Some Examples of Applications of a Microthermal Desorption Device in the Forensic Laboratory

Abstract:  Several applications of a microthermal desorption device for analysis of small forensic samples are presented. The method uses a solid phase microextraction holder with the fiber removed. In addition to samples of inks on paper, this device was successfully used for analysis of toners, various stains on bank notes, and lipstick stains on paper. Other small items encountered in a forensic science laboratory were also analyzed: particles of smokeless powder, particles of coffee, and automotive clear topcoat layer. The desorbed compounds were analyzed by gas chromatography with a flame ionization detector or by gas chromatography–mass spectrometry. This device can be used in connection with any kind of gas chromatograph. By selection of different injector temperatures, fractionated thermal desorption of samples is achieved. The procedure was demonstrated on samples of ballpoint pen ink of various age.     

The Stable Isotope Ratios of Marijuana. II. Strontium Isotopes Relate to Geographic Origin

Abstract:  Effectively addressing marijuana trade is aided by understanding marijuana geographic sources. We analyzed the ⁸⁷Sr/⁸⁶Sr of marijuana samples grown in 79 counties across the United States to determine if a primary geologic signal is retained in marijuana, which could therefore be useful for geographic sourcing. The marijuana results were compared with modeled bedrock ⁸⁷Sr/⁸⁶Sr values based on ⁸⁷Rb decay rates and a generalized geologic map of the U.S.A. A significant correlation was observed between marijuana ⁸⁷Sr/⁸⁶Sr and modeled bedrock ⁸⁷Sr/⁸⁶Sr. Although values clustered near the 1:1 relationship, there was a predominance of positive anomalies, perhaps attributable to carbonate bedrock. A small number of negative anomalies were also observed, which were generally associated with granitic bedrocks. These results suggest that strontium isotopes in marijuana record the geographic origins of marijuana, and that refinement of the base strontium map (or strontium isoscape) and improved understanding of other strontium sources would be productive.     

Photo‐ and Thermal‐Degradation Studies of Select Eccrine Fingerprint Constituents

Abstract: Photo‐ and thermal‐degradation studies on eccrine fingerprint components are presented herein. Dilute distinct solutions of urea, lactic acid, and seven amino acids were deposited on steel coupons and Teflon^® disks, exposed to artificial sunlight or heat, extracted, and analyzed. This aim of this study was to determine whether the investigated eccrine components, previously determined to be Raman active for a parallel study, experienced photo‐ or thermally induced degradation, and if so, to determine the rate and identify any detectable products. Neither the amino acids nor urea exhibited photo‐degradation; however, when heated for a period of three minutes, the onset of thermal‐degradation was initiated at 100°C for the amino acids and 100°C for urea. Lactic acid, the major polymerization initiator of superglue fuming, showed photochemical and thermal‐degradation. These results could be used for future development of new latent fingerprint visualization methods, especially when lactic acid is degraded.     

Unexpected Human Fatality Associated with Bed Bug (Hemiptera: Cimicidae) Heat Treatment

Thermal insect treatments can be an effective method of controlling cryptic insect pests, particularly bed bugs, in residential settings. The treatments require high heat over a sustained timeframe. Residents are not present during treatment but return after completion. An unexpected death was investigated following heat treatment for bed bugs in the home of an elderly female, found with a postmortem axillary temperature of 106.2°F (41.2°C) approximately 8 h after returning home. The cause of death was classified as hyperthermia with a contributory cause of hypertensive cardiovascular disease. The manner of death was an accident. The decedent had medical history and medications that could have impaired her ability to dissipate heat. Furthermore, the air conditioning inside the residence was not functional following treatment. Recommendations including education regarding heat stroke and treatment, re‐entry timeframes, and/or temperature thresholds are suggested to reduce the risk of heat‐related injury or death in vulnerable populations.     

Searching for Kin Amidst Tragedy—Disaster Victim Identification Operations for US Bangla Flight 211

The nature of air disasters includes factors that exacerbate challenges in the identification process. Of the 49 deceased in the US Bangla air crash in Kathmandu, Nepal, four were intact, 11 presented with burn injuries, another 11 presented with partial charring, and 23 were completely charred. Personal belongings were useful in the identification phases for all types of victims. Fingerprints were obtainable and useful in intact victims and victims with less severe burn injuries; medical and surgical information was useful in bodies with burn injuries; finally, dental findings were useful in cases of extensive charring. Other useful methods in the process included marks of identification, physical features, and exclusion. In certain resource‐limited settings, especially in closed population disasters, where scientific identification (DNA, dental records, etc.) is not currently available, personal belongings, clothing, and physical findings analyzed by an identification team using a structured organization may be cautiously used as the primary means of identification.