High-energy synchrotron radiation x-ray fluorescence spectrometry (SR-XRF) utilizing 116 keV x-rays was used to characterize titanium dioxide pigments (rutile) and automotive white paint fragments for forensic examination. The technique allowed analysis of K lines of 9 trace elements in 18 titanium dioxide pigments (rutile), and 10 trace elements in finish coat layers of seven automotive white paint fragments. High-field strength elements (HFSE) were found to strongly reflect the origin of the titanium dioxide (TiO(2)) pigments, and could be used as effective parameters for discrimination and classification of the pigments and paint fragments. A pairwise comparison of the finish coat layers of seven automotive white paint fragments was performed. The trace elements in the finish coat layers detected by the high-energy SR-XRF were especially effective for identification. By introducing the trace element information of primer and electrocoat layers, all the automotive white paint fragments could be discriminated by this technique.

Contrasting or enhancing of cyanoacrylate ester-fumed latent fingerprints deposited on solvent-sensitive materials such as oil marker writings and rough surface materials such as unglazed earthenware is not easy by conventional dye solutions dipping or dye powder dusting. In this study, a new vapor-phase staining method using p-dimethylaminobenzaldehyde (DMAB) is proposed for staining such materials. DMAB has high volatility and selective absorbability to cyanoacrylate-fumed fingerprints, so that cyanoacrylate-treated samples can be easily stained by leaving them simply in a closed container along with DMAB crystals for 48-96 h at room temperature or in conjunction with the use of mild heating. The stained fingerprint could be excited by UV irradiation (365 nm), and the fluorescent fingerprint was photographed through a UV cut-off filter (420 nm). The new method achieved minimally destructive fluorescent staining for the solvent-sensitive samples and the rough surfaced samples.

Optimization of a light emitting diode (LED)-based excitation system for the detection of pretreated fingerprint fluorescence is described. Fluorescent ridges can usually be excited by irradiation with forensic light sources such as xenon arc lamps or quartz-halogen lamps with high-power output and suitable filters. However, they are too expensive for many crime laboratories in smaller organizations. We concentrated on LEDs which have advantages over conventional light sources in that they are simpler and of lower cost, but the power output and quality of each individual LED unit is not sufficient for the detection of weak fluorescent ridges. To resolve this subject, blue and green LED arrays composed of ninety LED units were adopted and suitable low pass filters for them were designed. An experimental system, consisting of blue and green LED arrays with the suitable low pass filters for illumination, high pass filters for viewing, a digital camera and a computer, was tested. The fluorescent images of cyanoacrylate ester fumed ⁄ rhodamine 6G stained fingerprint on white polyethylene sheet and weak fluorescent ridges of ninhydrin ⁄ indium chloride treated fingerprint on white paper were successfully detected and photographed. It was shown that the improvement of LED beam in intensity and quality can compensate the disadvantages, resulting in well-contrasted images.KEYWORDS: forensic science, fingerprint fluorescence, LEDs array excitation, low pass filter, cyanoacrylate ester ⁄ rhodamine 6G, ninhydrin ⁄ indium chloride Fingerprint detection still holds the most important place in crime investigation and attempts to develop new methods for visualization of latent fingerprints have been continued throughout the world.In daily fingerprint work, weak fingerprints have often been resolved by utilizing fluorescent enhancement methods (1) such as fluorescent compound dusting, fluorescent dye staining employed together with cyanoacrylate ester fuming, and zinc chloride (ZnC1 2 ) treatment of Ruhemann's Purple (RP) fingerprints developed with ninhydrin. The other reagents such as o-phthalaldehyde (2,3), 7-benzylamino-4-nitrobenz-2-oxa-1,3-diazole (BBD) (4), 1,8-diaza-9-fluorenone (DFO) (5) were also reported to be applied to untreated latent fingerprints mainly on porous substrates resulting in fluorescent compounds on the fingerprint ridge.These fluorescent dyes and fluorescent compounds on the fingerprint ridge can be excited by irradiation with forensic light sources. In many cases, a xenon arc lamp or a quartz-halogen lamp with high-power output and suitable filters, and sometimes an appropriate laser, are used as the light source. These light systems do work quite well but are expensive for many crime laboratories in smaller organizations, especially for many identification sections in police departments. In addition to this, photographing of weak fluorescence has been rather avoided in Japan owing to its complicated operation. So an inexpensive, simplified, and reasonably efficient light system has been in...