Effect of Temperature on the Visualization by Digital Color Mapping of Latent Fingerprint Deposits on Metal

Visualization of fingerprint deposits by digital color mapping of light reflected from the surface of heated brass, copper, aluminum, and tin has been investigated using Adobe^® Photoshop^®. Metals were heated to a range of temperatures (T) between 50°C and 500°C in 50°C intervals with enhancement being optimal when the metals are heated to 250°C, 350°C, 50°C, and 300°C, respectively, and the hue values adjusted to 247°, 245°, 5°, and 34°, respectively. Fingerprint visualization after color mapping was not degraded by subsequent washing of the metals and color mapping did not compromise the visibility of the fingerprint for all values of T. The optimum value of T for fingerprint visibility is significantly dependent of the standard reduction potential of the metal with Kendall's Tau (τ) = 0.953 (p < 0.001). For brass, this correlation is obtained when considering the standard reduction potential of zinc rather than copper.     

A Calibration Test for Latent Fingerprint Development on Thermal Paper

A calibration test is described for monitoring the operation of equipment used to develop latent fingerprints on thermal paper by the application of either controlled or uncontrolled heat. A working solution of a water/glycerol emulsion and butylene glycol is applied to thermal paper by means of either a vinyl stamp and pad, or a marker pen. Varying the amount of butylene glycol enables the thermal paper to change color at different temperatures between approximately 40 and 60°C, which is below the normal color change temperature of the paper. The described test may be used to verify the correct operation, at different temperatures, of a controlled heat source during and after fingerprint development (such as the Hot Print System) or to monitor the paper temperature with an uncontrolled heat source (such as a warm air blower), thereby avoiding unintentional coloring of the entire paper surface.     

Analysis of friction ridge evidence for trace amounts of paracetamol in various pharmaceutical industries by Raman spectroscopy

The detection of potentially harmful substances presents a multifaceted challenge. On one hand, it can directly save lives, on the other, it can significantly aid and enhance police work, thereby increasing the effectiveness of investigations. The research conducted in this study primarily aims to identify paracetamol in fingerprints, considering situations involving direct contact of a person with paracetamol either chronically or in a single dose. The identification procedure presented, utilizing Raman spectroscopy, aims to rapidly detect the xenobiotic following ingestion by an individual, which involves touching the tablet with their fingers—this can be termed as touch evidence in forensic science investigations. Additionally, the authors focus on assessing the impact of additives present in drugs containing paracetamol as the main active ingredient. The screening results obtained will enable us to analyze the composition of drugs in terms of potentially toxic substances, and their influence on the physicochemical activity of the active substance. We successfully identified the paracetamol molecule using a noninvasive forensic trace detection method. Samples in the form of common drugs containing 500 mg of paracetamol were studied. Throughout the study, comprehensive validation of the method was ensured through the utilization of a statistical model, which excluded sensitivity to the presence of other substances, whether additives or from the external environment. The proposed approach to trace the content of substances in fingerprint using Raman scattering analysis provides a useful starting point to enhance current analytical methods not only in forensic science but also in toxicology.     

短波紫外反射照相显现铝制板汗液指印效果差异分析

目的 分析短波紫外反射照相显现铝制板框上汗液指印效果差异形成的原因.方法 利用短波紫外反射照相并用不同的打光方式对铝制板框汗液指印进行显现.结果 打光的角度不同,汗液指印的显现效果截然不同,并且在小角度入射的情况下,铝制板框上的汗液指印显现效果和玻璃载玻片上的汗液指印显现效果也明显不同,铝对短波紫外高反射率的特性引起了汗液指印显现效果的不同.结论 针对铝制板类的检材,在利用短波紫外进行汗液指印显现时需要明确不同情况下相应的显现效果.     

新型荧光502粉末显现手印技术的改进研究

目的 对新型粉末状荧光502显现手印的方法进行进一步探索和完善,确保其高效便捷和科学准确.方法 将PolyCyano UV粉末加热至230℃使其升华,待该粉末在手印纹线上聚合附着后用长波紫外线或蓝光激发拍照,并与初步研究结果相比较.结果 大部分非渗透性光滑客体表面上的汗潜手印均有很好的显现效果.结论 该方法使显现流程更加高效便捷、显现时间短、无需二次染色增强、不破坏生物检材,适合推广使用.     

基于内存比对的CAFIS系统指纹比对方法改进研究

目的研究改进现有指纹自动识别系统的比对速度。方法将大量的比对数据提前加载到内存中,结合多线程并行计算,达到一次加载多次使用的目的。结果多组测试数据证明内存比对方式可以有效减少访存时间,提高了整体比对速度。结论指纹系统的内存比对方式是快速可行的比对方法。     

新型荧光502粉末与502胶＋荧光染色显现潜在手印的比较

目的对新型荧光502粉末显现非渗透性光滑客体表面潜手印的一步荧光502显现新技术和传统502胶水熏显＋荧光染料染色显现手印技术进行比较研究。方法比较实验研究,对荧光502粉末和502胶水使用同一自动熏显柜先后进行熏显,荧光502粉末熏显结束后直接在蓝光灯下激发进行观察和拍照;502胶水在熏显完成和聚合物完全固化后使用罗丹明6G和BBD溶液进行荧光染色,再进行光致荧光照相。结果一步熏显和二次染色的显现效果基本相同,但两者的显现效果也因检材性质和遗留时间的不同而存在一些差别。结论新型荧光502粉末可以作为一种显现非渗透性光滑客体表面上潜手印的常用方法,尽管新方法对某些客体的显现效果并不好,但对大多数客体来说,其显现效果并不弱于二次染色的方法,并且使用新型荧光502粉末进行一步熏显不会引入有机溶剂,不会引起502聚合物的溶解或造成破坏,确保了纹线及其细节特征不被损坏,也避免了染色后因漂洗不当使手印纹线被冲掉的可能,还不会破坏脱落细胞等生物检材。     

基于机器学习的指纹识别技术

指纹识别技术是重要的刑事侦查手段,也是图像识别领域具有代表性的一类模式识别问题。本文通过对机器学习算法的研究和分析,将目前流行的学习算法应用于指纹识别问题,以提高指纹识别系统的识别速度和学习算法的泛化能力。     

Vapor-phase staining of cyanoacrylate-fumed latent fingerprints using p-dimethylaminobenzaldehyde

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.     

建立火场样品中汽油残留物ATD-GC-MS检验结果的评价方法

目的建立火场中汽油燃烧残留物ATD-GC-MS检验结果评价方法。方法将模拟燃烧样品用ATD-GC-MS法检验,检验结果通过对芳烃、烷烃、茚满、和萘系列的4个特征离子色谱图与已知汽油作比较,并利用向量夹角法计算样品与汽油色谱指纹图的相似度来对检验结果作评价。结果有汽油作助燃剂的模拟燃烧样品与汽油色谱指纹图的相似度一般大于90%,无汽油作助燃剂的样品则在60%以下。结论利用样品的4个特征离子色谱图与已知汽油作比较,并结合样品与汽油色谱指纹图相似度的计算,能对检验结果作出客观、可靠和准确的评价。