硝酸银法显现汗潜手印时效问题的研究

本文通过试验阐明了用硝酸银法显现汗潜手印的时效问题。试验表明用硝酸银法可显出遗留在纸张上长达50天的汗潜手印,但显现效果因人而异,且受手印遗留者及周围环境等诸因素的影响。     

碘熏显现热敏纸上的汗潜手印

热敏纸作为一种特殊的客体,其传统显现普通纸张汗潜手印的显现方法,如(硝酸银显现法、茚三酮溶液法、DFO法等) ,都不能有效显现热敏纸上的汗潜手印。热敏纸遇到有机溶剂,药膜面上会产生黑色污染背景,影响指纹显现,甚至使整个膜面变黑,上面的手印消失。直接加热法显现热敏纸潜手印时,显现温度难以掌握,易污染检材,只能显现热敏纸膜面上的手印,背面的手印没法解决,对有效显现热敏纸上的手印有很大的局限。而碘熏法能克服上述不足,有效的显现热敏纸上的潜手印,此方法操作简便,显现效果较好,不仅能显现新鲜手印,还能显现保存较好的热敏纸上的…     

硝酸银、茚三酮、DFO法显现纸张上指印的效果比较

目的为有效的提高纸张上汗潜手印的显现率。方法根据汗潜手印的显现原理,针对不同的纸张,分别运用硝酸银、茚三酮与DFO（1,8-二氮芴-9-酮）3种显现方法进行了实验,并对实验结果进行了分析比较。重点分析了这3种方法在显现不同纸张、不同遗留时间、不同汗液量的汗潜手印时的效果及其适用范围。结果为改善渗透性客体上的汗潜手印显现效果,提供科学的依据。     

茚三酮、硝酸银显现热敏纸上汗液手印

由于热敏纸在商业、金融、医疗、交通等各领域上的广泛使用，办案中经常会遇到此类纸张上的手印显现和提取问题。因为多数热敏纸遇极性有机溶剂和高温会变色，破坏检材无法显现手印，近年来有不少关于显现热敏纸上的汗液手印的新方法出现，如茚三酮真空熏显法、氨基化合物漂洗法和红油O显现法等，但是这些方法使用的药品价格较贵，对操作过程和仪器要求较高，不便于推。笔者采用传统的茚三酮和硝酸银显现方法，对彩票、超市收银纸、火车票、     

一种改进的碘熏法-碘锌手印显现法

目的为解决传统碘熏法显出手印容易褪色、固定困难等问题。方法提出了一种改进的碘熏法-碘锌手印显现法，实验了不同反应物配比、不同客体材质对显现效果的影响；与常规碘熏法进行了对比实验；并考察了碘锌法显出手印的稳定性。结果碘锌手印显现法可以用于常见渗透性及非渗透性客体上新鲜汗潜手印的显现。该方法不必外加热源，携带、存储和应用更加便利；该方法显出的指纹纹线保存时间与传统碘熏法相比明显延长。结论碘锌手印显现法是一种高效、实用的手印显现方法。     

茚三酮一硝酸银混合显现法初探

茚三酮和硝酸银溶液均为刑事技术工作中常用的指纹显现试剂,笔者结合日常工作实践,试将二种溶液混合进行手印显现,达到明显效果,报告如下.     

饱和银氨溶液显现纸张上手印的研究

在犯罪现场中,经常涉及到各种纸张上手印的显现。以往多是利用硝酸银溶液及茚三酮溶液进行显现。硝酸银曝光不易控制,且硝酸银溶液与茚三酮溶液显出的手印往往出现断断续续的现象。饱和银氨溶液基本上克服了以上缺点,而且显现速度明显高于前两者。 1 显现原理 人体汗液中含有大量水份、部分无机盐以及少量有机物质。银氨溶液中含有银氨铬离子Ag(NO_3)_2~ ,它与卤离子发生反应生成卤化银,卤化银极易被感光,在光照     

用磁性刷刷显铁质物体上的手印

有关刑事科学技术方面的书籍中曾介绍了磁性粉末显现手印的适用范围，适用于油漆物面、瓷器、塑料、木制品、铝制品、纸张、钞票等物体上的手印显现。但是，很少提及用磁性粉末显现铁质物品上的手印。在实际工作中，笔者利用磁性刷刷显法，成功在铁质物品上提取到了多枚手印，效果很好，现向大家推荐。     

常用粉末显现手印的若干技巧

粉末显现法是利用新鲜汗液手印中含有的阴、阳离子,氨基酸、脂肪等,在与粉末接触时存在较强的亲和力而起附着作用,直接加染手印的一种物理方法。因此,使用此法显现前,要认真观察是由什么物质形成的手印,对不适用粉末显现的油脂、潜血、精斑等手印,要用其它相应的方法提取显现,以免破坏现场手印;在使用粉末显现手印的过程中,不仅要掌握规范的操作方法,而且要熟练地根据不同情况采取相应的显现技巧,才能达到理想的显现效果。笔者在实践中,针对一些造成手印显现不出或显现效果不佳的原因,在不破坏现场手印的前提下,将粉末显现手印加以灵活运用,提高了手印的显出率和显现质量。     

铬黑T显现潜血手印最优条件探讨

目的 以铬黑T为溶质，不同溶液为溶剂制备新型显现液，确定铬黑T溶液显现潜血手印的最佳配方及使用范围。方法 通过考察甲醇、二氯甲烷、丙酮、乙酸乙酯、无水乙醇、蒸馏水六种溶剂、不同的显现液浓度、潜血手印遗留时间、承痕体种类以及血液浓度等因素对显现效果的影响，建立最佳显现液体系并与传统染色法进行对比。结果0.020 mol/L的铬黑T-甲醇溶液显现效果最佳，采用浸泡法、滴显法、喷显法均能清晰显现皮革、玻璃片、瓷砖、红色塑料片、农夫山泉红色珠光膜上的潜血手印。与传统染色试剂氨基黑10B对比，铬黑T-甲醇显现液在显现稀释后的血液和陈旧潜血手印时效果更佳。结论 0.020mol/L的铬黑T-甲醇溶液为最佳显现配方，该方法显现效果好、适用范围较广、配合装置使用易于携带且无需后置处理，可供公安现场办案使用，具有较高的应用价值和应用前景。     

防止茚三酮溶液扩散纸张字迹的研究

目的 解决茚三酮溶液在显现手印同时对纸张上字迹产生扩散作的问题;方法 分别采用茚三酮丙酮溶液,茚三酮氟利昂溶液,茚三酮石油谜溶液,茚三酮庚烷溶液作比较。结果 钢笔字迹用4种溶液均不易扩散;纸张上其它成份字迹用后两种方法显现手印时可有效保存纸张上文字原貌。     

卫生纸上汗潜手印显现方法比较研究

目的通过比较实验来探寻卫生纸上汗潜手印的最佳显现方法,为实际工作提供指导性建议。方法选择市面上常见的四种卫生纸,在每种卫生纸上制作汗潜指印实验样本,分别将茚三酮溶液浸泡法与茚二酮溶液浸泡法、茚二酮溶液浸泡法与茚二酮溶液超声雾化法、茚二酮溶液超声雾化法与(对)-二甲(替)氨基肉桂醛(DMAC)显现纸冷熏法、茚二酮溶液浸泡法与红外加热显现法、茚二酮溶液超声雾化后加热显现法与室温显现法进行两两比较,分析显现效果。结果茚二酮显现的灵敏度和质量均优于其他几种方法,特别是超声雾化后室温显现,既能很好地显现手印又不影响后期的DNA检验。结论采取茚二酮超声雾化室温条件显现方法显现卫生纸上的汗潜手印具有显现效果好、设备条件要求低、操作性强的特点,在实际案件中可以借鉴应用。     

尼罗红显现潮湿纸张上油脂手印方法初探

目的探索显现潮湿纸张表面油脂手印的显现方法。方法取250枚纸张载体的油脂指印,分为AB-CDE 5组,分别用自来水浸泡不同时间后,用尼罗红工作液显现,并在465nm多波段光源下进行观察。结果 5组的显现率从56%～94%,表明显出率比较高。结论该方法简单实用,可用于案件检验。     

Chemical development of latent fingerprints: 1,2-indanedione has come of age

The performance of 1,2-indanedione as a latent fingerprint reagent on some types of paper was found to exceed that of DFO, the leading fluorogenic fingerprint reagent. It even exceeds the performance of the sequence, DFO, followed by ninhydrin. No new prints could be observed when ninhydrin was applied after indanedione. On a large number of actual exhibits (used checks) indanedione developed 46% more identifiable prints than the sequence DFO-ninhydrin. A standard procedure for fingerprint development by indanedione is proposed. Best results are obtained with a 0.2% indanedione solution in HFE7100 solvent containing 7% ethyl acetate, but no acetic acid. It can be recommended to start using 1,2-indanedione, which is already commercially available, in actual fingerprint casework.     

Comparison of Rehydration Techniques for Fingerprinting the Deceased after Mummification

Postmortem decay causes fingertip decomposition, desiccation, shriveling, and rigidity, reducing the possibility of obtaining sufficiently clear fingerprints for identification. In this study, five rehydration solutions (ammonium hydroxide, sodium carbonate, potassium hydroxide, urea, and warm water) followed by three fingerprint recording methods (photograph, inking roll, and dusting tape) were investigated to process mummified fingertips from an unidentified cadaver. The results show that sodium carbonate treatment is the most effective for minutiae restoration, followed by ammonium hydroxide treatment. This study also demonstrates that even those fingertips that previously failed in urea solution, 1% potassium hydroxide solution, and warm water treatment could be further improved with sodium carbonate solution to obtain qualified minutiae for fingerprint matching. The optimal procedure is rehydrating the desiccated fingertips with sodium carbonate solution for 24 h followed by dusting the finger and transferring the print to adhesive tape.     

The thermodynamics of latent fingerprint corrosion of metal elements and alloys

Redox reactions taking place between the surface of a metal and fingerprint residue have been expressed thermodynamically in terms of both the Nernst equation for reduction potential and the complexation constant for the formation of complex metal halide ions in aqueous solution. These expressions are used to explain experimental results for the corrosion of 10 different metal elements by fingerprint residue in air at room temperature. Corrosion of noble metals, such as silver and gold, supports the proposition that the degree of metal corrosion is enhanced by the presence of chloride ions in eccrine sweat. Extending the experiments to include 10 metal alloys enabled the construction of a fingerprint corrosion series for 20 different metals. Fingerprint corrosion on metals alloyed with > approximately 40% copper was found to display third level fingerprint detail. A comparison of both conventional ink on paper and digital (Livescan) fingerprinting techniques with fingerprints deposited on 9 Karat gold alloy has shown that gold alloy depositions are least susceptible to third level detail obliteration by poor fingerprint capturing techniques.     

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.     

纸张上潜在手印三种前处理方法对DNA检验的影响

目的通过比较常见纸张上潜在手印盲提法与显现后精准提取法的接触DNA检出率,探讨常见纸张上接触DNA前处理的优选方案。方法比较五种常见纸张上使用盲提法和显现潜在手印(茚二酮显现法、茚三酮熏显法)后精准提取法采集的接触DNA样本检出率。结果粗糙日历纸盲提的接触DNA检出率为17.8%,通过茚二酮法和茚三酮法显现的潜在手印所提取的DNA检出率分别为75.6%、77.8%;光滑日历纸三种方法所提取的接触DNA检出率为4.4%、11.1%、11.1%;A4复印纸三种方法接触DNA检出率为20%、37.8%、66.7%;牛皮纸三种方法接触DNA检出率为20%、68.9%、64.4%;快递纸袋的三种方法接触DNA检出率为2.2%、6.7%、46.7%。结论不同纸张上潜在手印经显现后接触DNA检出率不同,通过茚二酮或茚三酮显示潜在手印后精准提取DNA的前处理方法相较于盲提法的接触DNA检出率高。实战中可应用此类方法同时获得手印与DNA分型,以有效提高证据力。     

Improvement in Latent Fingerprint Detection on Thermal Paper Using a One‐Step Ninhydrin Treatment with Polyvinylpyrrolidones (PVP)

Abstract: Most thermosensitive surfaces of thermal paper turn black when they come into contact with polar organic solvents such as are used in ninhydrin petroleum benzin solution. This dark staining reduces the contrast between the developed fingerprint and the background to such an extent that the identification process becomes very difficult. Integrating polyvinylpyrrolidones (PVP) into a ninhydrin solution prevents the black staining, and the developed fingerprints appear in clear contrast to the background. The new ninhydrin solution containing PVP is successful compared to the two‐step ninhydrin–acetone washing method for thermal paper which is popular in Germany.     

微晶荧光乳浊液显现血、汗指纹的研究

目的　显现非渗透性和半渗透性客体上的血指纹、汗潜指纹。方法　应用微晶小颗粒荧光乳浊液显现血、汗指纹。结果　对常见的各种非渗透性和半渗透性客体上的新鲜和陈旧的血、汗指纹均可显出。结论　该方法与传统的物理显现方法相比较在于显出效果基本不受指纹遗留时间和客体的性质及表面颜色的影响 ,并且此方法实用、可靠 ,同时该配方还可用于非渗透性和半渗透性客体上涉油指纹的显现 ,是常见客体上血、汗指纹显现的一个重要突破