502熏显法显现车辆内手印

基层技术部门每年都要勘查很多的汽车现场,遇到最棘手的问题是车内的手印处理。笔者介绍一种车内潜在手印显现方法。采取车辆内用502熏显,寻找、提取车内各部位的汗潜手印。车内光洁部位遗留的手印,皮革、塑料、金属材料表面的显现效果比较满意。     

现场疑有手印部位的“502”胶熏显法

现场勘查在遇到需要“502”胶熏显的指纹时,通常将客体放在容器中熏显,无法提取时就用滤纸贴附熏显。滤纸熏显这种方法使指纹显现得比较快,同时也存在难以把握之处。主要存在3个方面的问题:一是“502”胶滴在滤纸上的干湿程度较难掌握。以往要使“502”胶滴在滤纸上后,滤纸贴在客体上并在熏显过程中,不会将“502”胶转移到客体上从而破坏客体上的指纹,有时需要多次试验。如在现场实际操作过程中,稍没掌握好,就很容易使滤纸上的“502”转移到客体上破坏指纹。好,滤纸上的“502”胶就已固化,特别是在熏显较陈旧的指纹时。三是熏显好坏难以掌握…     

拓展502熏显技术应用范围的探讨

上世纪80年代初期,502熏显技术开始广泛应用于犯罪现场的勘验工作。至今,在各类犯罪现场的勘验中确实发挥了不小的作用。目前大多数现场上提取的原物,基本上都习惯用502技术进行处理。如何在各种条件下、各种客体上进一步发挥其应有效能,一直是专业人士引以关注的课题。从理论上分析,502胶中的氰烯酸乙酯分子能与人体汗液成分聚合形成白色可见产物,使物体表面上的潜手印被固定,通常提取的方法是拍照。由于502胶加热后生成的白色物质附着在汗液指掌纹上,出现在深色平面客体上往往拍照效果较好,但在浅色、白色和花(杂)色客体上所形成的反差效…     

“502”现场熏显简易装置的制作

“502”熏显法是我国基层痕检技术员使用较为普遍的指纹显现方法。“502”熏显的方法多为在密闭的容器中进行冷熏和热熏,另外对于不能移动的客体(如墙面、地面等)上的指纹,可以用滤纸贴附熏显法来显现,该法具有快速、简捷的优点,特别是在时效上有着不可取代的优势。但是,滤纸在被502胶水浸透变软后难以把持,与客体的距离也难以控制,稍有不慎会破坏指纹。所以笔者在经过多次试验和实践后向广大基层技术员提供一种简易的滤纸熏显支架。1简易支架的制作方法(1)原料选用质地较硬的硬纸即可,如果一面贴有塑料薄膜更佳,剪成长16cm,宽3cm的长方型纸…     

加热502胶熏显手印的改进方法

加热502胶水熏显手印，通常需要将客体置于502熏显柜、聚乙烯薄膜罩等密封容器中进行，使用这类显现器材的优势是熏染速度快，数量多，一次可同时熏染多个客体，但现场手印的承载客体千差万别，对一些较为特殊的客体，应用上述密封加热方法，有时存在一些不足：①对体积较大或不可提取的客体，无法在熏显柜、聚乙烯薄膜罩等密封容器中进行加热熏显；     

“502”真空熏显手印技术的应用现状

在我国,“502”加温加湿熏显手印技术已广为普及,但“502”真空熏显手印技术人们了解很少。本文通过介绍“502”熏显手印技术的发展,着重介绍真空熏显方法的特点。     

“502”加膜一染色法显现油质手印

目的探索方便快捷并有效的油质手印显现方法。方法用“502”熏显常见玻璃、粗糙皮革等不同客体上不同遗留时间的油汗手印和多油手印,加染后用透明胶带粘取。结果显现了30天左右大多数非渗透性客体上的油质加层手印,10天左右渗透性客体上的油质渐层手印。结论本方法适用于油质加层手印及部分油质渐层手印的显现,显出手印清晰,流畅,不破坏手印。     

利用502熏显柜显现浸泡文件1例

浸泡文件的显现在日常案例中比较少见,笔者在实践中成功的显现了较大量的浸泡文件,显现效果很好,希望能给广大文检工作者提供帮助。1案例资料 2007年12月,受相关办案单位的委托,请求显现某案件中被水浸泡的笔记本。经目测观察,该笔记本被送检单位在通风处自然阴干,阴干后纸张基本自动分离,不存在粘连和损坏现象,但由于笔记本被水浸泡严重     

蜡质客体上汗潜手印的显现

目的建立蜡质客体上汗潜手印的显现方法;方法遗留在蜡质客体上的汗潜手印,经适量“502”熏显后,用较高浓度的BBD溶液进行染色,在多波段光源的激发下以增强显现效果。结果遗留在蜡面上10天以内的汗潜手印可得到理想结果;结论该方法方便易行,并成功用于检案。     

纳米CdSe增强“502”胶显现新鲜手印方法研究

本文利用纳米CdSe溶液显现了白色塑料、塑钢上面的油脂手印,比较了该试剂和传统试剂的增显效果,初步探讨了纳米CdSe溶液增强“502”胶显现手印的应用前景.     

彩色背景客体上手印的显现方法

目的利用真空金属镀膜法和＂502＂胶熏显法之间的空间互补性原理,考察显现杂色背景客体表面潜手印过程中遇到的杂色背景干扰问题。方法对杂色背景客体表面的同一枚手印分别采用紫外照相、＂502＂胶熏显、真空镀膜方法处理,比较去除背景干扰能力。结果采用＂502＂胶熏显,真空金属镀膜后期增强处理,能够使指纹纹线清晰连贯,并能有效消除背景杂色干扰。结论该方法可有效消除背景杂色干扰,清晰显现有彩色背景的易拉罐、照片纸等客体上的指纹。     

Nanoscale analysis of the interaction between cyanoacrylate and vacuum metal deposition in the development of latent fingermarks on low-density polyethylene

Vacuum metal deposition (VMD) has been previously demonstrated as an effective development technique for latent fingermarks and in some cases has been shown to enhance prints developed with cyanoacrylate (CA) (superglue) fuming. This work utilizes scanning electron microscopy (SEM) to investigate the interactions of the two development techniques when applied to latent fingermarks on low-density polyethylene. CA is shown to act principally on the eccrine deposits around sweat pores, where polymerization results in long polymer fibrils a few 100 nm in width. Subsequent VMD processing results in additional areas of development, for example, between pores. However, the primary mode of deposition of zinc is by interaction with the polymerized CA, the fibrils of which become decorated with zinc nanoparticles. Areas with limited CA deposition and no significant polymerization are also enhanced with the VMD process, resulting in increased print development.     

Enhancing the quality of aged latent fingerprints developed by superglue fuming: loss and replenishment of initiator

The recovery and identification of latent fingerprints from a crime scene are crucial to many investigations. The cyanoacrylate (superglue) fuming method (CFM), which develops fingerprints by growing a polymer coating over the print residue, is a powerful method but encounters severe limitations when prints are aged or exposed to harsh environmental conditions. We examine the aging process and how the changes that occur to a fingerprint residue over time influence the growth of polymer during development. We identify loss of initiator by erosion and degradation that, when coupled with a loss of water from the print residue, result in a decreased ability to polymerize ethylcyanoacrylate. Then, we present a methodology by which the ability of aged latent fingerprints to polymerize ethylcyanoacrylate is recovered. Two print enhancement agents, acetic acid and ammonia, are demonstrated to improve the growth of polymer from the print ridges by over an order of magnitude, while retaining the integrity of the print structure. Comparison between the two enhancement agents indicate that the enhancement occurs due to ridge coating by the ammonia or acetic acid and pH control of the latent print.     

四氧化钌显现潜手印研究

目的探索显现潜手印的新方法。方法通过实验研究提出四氧化钌显现方法。结果对遗留在白纸、报纸、玻璃及木板等4种客体上的新鲜及陈旧潜手印的显现实验，得出比较理想的显现效果。     

Development of latent fingermarks on thermal paper: Preliminary investigation into use of iodine fuming

Thermal paper finds its extensive use in the modern day life and could act as a vital piece of physical evidence carrying latent fingermarks. A large number of citations are available in literature suggesting various techniques to develop these marks but all are suffering with one or the other drawbacks such as complex and cumbersome procedure, pre- or post-treatment, background coloration and efficiency to develop aged fingermarks. In present study, a very simple and novel method involving iodine fuming has been suggested to develop fingermarks which were not only permanent but also without any background coloration. The suggested method does not involve any pre- or post-treatment of the substrate and was able to develop very old fingermarks (upto >1 year). In this study an attempt has been made to explain the reaction mechanism of the process. In case of different types of thermal papers, presence of different substituents on leuco dye (lactone ring) structure resulted in development of different colored fingermarks upon reaction with iodine. Sebaceous material laden marks have been found to be more intensely developed as compared to eccrine marks, and the difference was more pronounced in case of aged fingermarks.     

PAMAM G7.0的制备及在非渗透性表面手印显现中的应用

目的探索一种非渗透性表面手印显现的新方法。方法根据现有方法合成第七代聚酰胺-胺（PAMAM G7.0）树形分子材料,并使用荧光光谱法对产物进行荧光测试;将合成材料对多种客体表面、不同遗留时间的手印进行显现,并将显现结果与粉末法和传统的荧光染料法进行比对。结果实验表明该荧光材料在365nm光激发下可以发出较强的可见荧光;与粉末法和传统的荧光染料法相比,PAMAM G7.0可以同手印残留物进行高选择性结合,手印纹线与背景之间的反差大。结论PAMAMG7.0可以有效地显出非渗透性客体表面的手印。     

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。     

真空镀膜中膜系选择对潜手印显现的影响

目的探究在真空镀膜中不同镀膜材料能否显现出潜手印并比较不同镀膜金属显现手印的效果。方法使用不同的镀膜金属显现多种类型客体表面的潜手印。结果存在可替换镀膜材料。结论可替换镀膜金属对潜手印显现的效果良好,纹线清晰连贯,背景反差大,并对特定客体上的手印显现极具优势。