平面扫描技术在尿渍鞋印提取中的应用研究

目的应用平面扫描技术建立尿渍鞋印的光学无损提取方法。方法通过调整光源入射角度和反射光接收角度等参数,运用3种平面扫描方法提取大理石、地板革和瓷砖等6种客体上遗留的尿渍鞋印。结果基于平面扫描技术的尿渍鞋印提取方法,显著增加了痕迹与承痕客体之间的亮度反差,消除或减弱承痕客体背景干扰。比较筛选得到了大理石、地板革和瓷砖等客体上尿渍鞋印的最佳平面扫描方法。结论平面扫描方法可作为一种光学无损方法用于尿渍鞋印的提取。     

灰尘鞋印直显与荧光显现研究

本文根据邻菲(口罗)啉在弱酸条件下与Fe~(2 )反应生成稳定的桔红色给合物的原理,对遗留在各种纸张、本色木、地板砖.地板革等承受客体上的灰尘鞋印进行显现,获得较佳效果.对微弱或潜在灰尘鞋印,用上述方法处理后,再用荧光粉末刷涂,用多波段光源显现效果更佳.     

曲面指印的拍摄与处理

刑事现场勘验过程中，经常会遇到已经发现或显现了的指印很难提取下来，这样的情况其中大部分属曲面指印。这里所说的曲面指印是指遗留于某一客体、并且该客体的指印区域表面为非单一平面上的各种指印。曲面上的水渍、油污、灰尘、血迹、熏显处理过的或曲度大的指印，     

油迹光滑非渗透客体上灰尘鞋印的提取

笔者通过长期的工作积累和实践总结,经多次实验后,总结出对于油迹光滑非渗透客体上遗留的灰尘加层鞋印,利用银粉或磁性粉显现效果较理想,方法简便,材料消耗少,显现的鞋印花纹清晰,易提取,保存时间长,是一种对于油迹光滑非渗透客体上遗留的灰尘加层鞋印提取之有效的好方法。1显现原理此法利用油脂对粉末的粘附性以显现鞋印。当鞋与薄油脂相接触时,由于鞋底的压力和鞋底上的灰尘的作用,使得与鞋底花纹接触处与未接触处的油脂厚度发生变化,而且由于鞋底各部压力不同也使重压部位与其它部位油脂厚度不同,另外鞋印上灰尘遗留在客体上形成加层灰尘…     

1例现场鞋印两次检验认定的体会

1案情简介2002年4月28日,仙桃市某街道居民朱某的2个儿子在家里吃完早餐后相继中毒后死亡。技术人员在朱家剩饭内检测出鼠药“毒鼠强”(俗称“424”鼠药,剧毒)。勘查现场时,在受害人家的厨房内水泥地面上发现并提取了新鲜水渍平面鞋印二枚。经过周密仔细的调查,摸排出了嫌疑人陈某(男,30岁,该地居民)。4月29日晚上,在传唤陈某之前,密取了陈穿用的一双干净球鞋,依据鞋底磨损特征的特定性,认定现场上水渍平面鞋印为陈所留。同时,又提取了陈脚上所穿的球鞋,经从形态痕迹的角度认定,现场鞋印就是陈脚上的球鞋所留。在铁的事实面前,嫌疑人陈某对…     

同一人穿不同鞋形成足迹的检验

1　问题的提出2 0 0 2年 4月 2 8日 ,某街道居民朱某两个儿子在家里吃早餐后相继中毒死亡。技术人员在朱家剩饭内检测出鼠药“毒鼠强”(俗称“4 2 4”鼠药 ,剧毒 )。现场勘查 ,在受害人家的厨房水泥地面上发现并提取了新鲜水渍平面鞋印二枚。侦察人员经过周密仔细的调查 ,摸排出了嫌疑人陈某 (男 ,30岁 ,当地居民 )。 4月 2 9日晚上 ,在传唤陈之前 ,在陈家密取了陈穿用的一双干净球鞋 ,依据鞋底磨损特征的特定性 ,认定现场上水渍平面鞋印为陈所留。据此 ,连夜对陈进行突审。与此同时 ,又提取了陈脚上所穿的球鞋。经检验 ,从形态痕迹的角度认…     

瓷砖上浅层鞋印的提取方法

瓷砖是居民家中常用的装修材料,一旦发生盗窃案,理论上在瓷砖上应该留下大量的鞋印,尤其是翻厨房窗户人室案件,在灶台瓷砖会留下鞋印。但是在实际工作中地面上很难发现鞋印,即使发现鞋印,也很难拍照提取,用静电吸附器效果也不好。这主要是因为犯罪嫌疑人鞋上灰尘本来就很少,粘附在瓷砖上就更少了,加上瓷砖大部分是浅色的和灰尘颜色很接近,反差小,就很难发现、提取。     

尿渍足迹的碘联雾化镀膜法增强技术研究

目的 探索尿渍足迹快捷显现技术;方法 制作500枚尿渍足迹,用IDEA碘联雾化镀膜法对地板表面上不同遗留时间和遗留量的尿渍足迹进行雾化镀膜处理;结果 0～7d内的尿渍足迹在30s全部显现,特征清晰连贯、背景反差明显,显出率达100％;结论 该方法显现尿渍足迹快速、操作简单,十分适合于基层部门刑事科学技术人员操作使用     

利用盲色片消除背底花纹对灰尘鞋印的影响

1 前言 对塑料有色花纹椅面上罪犯遗留的灰尘鞋印的提取,将为案件的侦破以及串并案件提供重要线索,笔者将结合案例,介绍利用盲色片的感光特性来拍摄提取有色花纹背底上灰尘鞋印的方法。 2 拍照原理 盲色片具有感光度低,颗粒度细,宽容度小,反差系数大,解像力高的感光特性,其感光乳剂中的感光特质是溴化银及少量碘化银的混合,没有加入光学增感剂,所以,盲色片只能感受蓝色光、紫色光以及部份紫外光,对其它色光不感光或感     

匈牙利红增强显现血潜鞋印的研究

目的建立一种增强显现血潜鞋印的新方法——匈牙利红显色法。方法根据匈牙利红增强显现血潜鞋印原理,采用固定、染色、冲洗、提取进行显现。结果匈牙利红对非渗透性客体上的血潜印痕增强显现效果明显,但对白纸、织物等非渗透性客体上的潜血印痕没有明显效果。结论可作为一种补充方法用于潜血印痕的提取。     

A Comparison of Enhancement Techniques for Footwear Impressions on Dark and Patterned Fabrics,

The use of chemical enhancement techniques on porous substrates, such as fabrics, poses several challenges predominantly due to the occurrence of background staining and diffusion as well as visualization difficulties. A range of readily available chemical and lighting techniques were utilized to enhance footwear impressions made in blood, soil, and urine on dark and patterned fabrics. Footwear impressions were all prepared at a set force using a specifically built footwear rig. In most cases, results demonstrated that fluorescent chemical techniques were required for visualization as nonfluorescent techniques provided little or no contrast with the background. Occasionally, this contrast was improved by oblique lighting. Successful results were obtained for the enhancement of footwear impressions in blood; however, the enhancement of footwear impressions in urine and soil on dark and patterned fabrics was much more limited. The results demonstrate that visualization and fluorescent enhancement on porous substrates such as fabrics is possible.     

Chemical enhancement of footwear impressions in blood on fabric — Part 2: Peroxidase reagents

This study investigates the optimisation of peroxidase based enhancement techniques for footwear impressions made in blood on various fabric surfaces. Four different haem reagents: leuco crystal violet (LCV), leuco malachite green (LMG), fluorescein and luminol were used to enhance the blood contaminated impressions.The enhancement techniques in this study were used successfully to enhance the impressions in blood on light coloured surfaces, however, only fluorescent and/or chemiluminescent techniques allowed visualisation on dark coloured fabrics, denim and leather. Luminol was the only technique to enhance footwear impressions made in blood on all the fabrics investigated in this study.     

Chemical enhancement of footwear impressions in blood on fabric — Part 3: Amino acid staining

Enhancement of footwear impressions, using ninhydrin or ninhydrin analogues is not considered common practice and such techniques are generally used to target amino acids present in fingermarks where the reaction gives rise to colour and possibly fluorescence. Ninhydrin and two of its analogues were used for the enhancement of footwear impressions in blood on various types, colours and porosities of fabric. Test footwear impressions on fabric were prepared using a specifically built rig to minimise the variability between each impression. Ninhydrin enhancement of footwear impressions in blood on light coloured fabric yielded good enhancement results, however the contrast was weak or non-existent on dark coloured fabrics. Other ninhydrin analogues which have the advantage of fluorescence failed to enhance the impressions in blood on all fabrics. The sequential treatment of impressions in blood on fabric with other blood enhancing reagents (e.g. protein stains and heme reagents) was also investigated.     

Collection of Wet‐Origin Footwear Impressions on Various Surfaces Using an Electrostatic Dust Print Lifter

Electrostatic dust print lift method is known to be able to recover only dry‐origin footwear impression. However, the wet‐origin footwear impression could also be recovered using this method. As the amount of dust accumulated before deposition of the wet‐origin footwear impression increased, the intensity of the footwear impression lifted with this method became stronger. If the footwear impression is not affected by moisture after it is made, the 28‐h old wet‐origin footwear impression could be recovered using this method. The intensity of the lifted footwear impression did not decrease significantly even when the number of sequential steps increased as long as the shoe sole is wet. However, when the moisture on the shoe sole depleted, the intensity of the footwear impression decreased sharply. This method has the advantage of being able to enhance the footwear impression without being affected by the footwear impressions deposited in the past.     

Chemical enhancement of footwear impressions in urine on fabric

A range of chemical techniques were utilised for the enhancement of footwear impressions deposited on a variety of fabric types of different colours with urine as a contaminant. A semi-automated stamping device was used to deliver test impressions at a set force to minimise the variability between impressions; multiple impressions were produced and enhanced by each reagent to determine the repeatability of the enhancement. Urine samples from different donors were analysed using a spectrofluorophotometer revealing differences between individuals. Results indicated that the enhancement of footwear impressions in urine was possible using amino acid staining techniques whereas protein stains failed to achieve successful enhancement.     

Evaluation and comparison of the electrostatic dust print lifter and the electrostatic detection apparatus on the development of footwear impressions on paper

The Electrostatic Dust Print Lifter (EDPL) and the Electrostatic Detection Apparatus(2) (ESDA(2)) were compared to determine if both processes could be used to develop footwear impressions of the same or similar quality and in what order they should be used to develop the highest quality footwear impression. The sensitivity of each technique was also evaluated. The quality of the footwear impressions developed was determined by comparing 25 individual characteristics present on the known shoe to the footwear impressions developed using each technique. The footwear impressions were made by stepping on paper placed over several different surfaces, which included: linoleum, industrial Berber carpet, nylon carpet placed over a (3/8)-in. pad, ceramic tile, cardboard, 1-in. foam, 4-in. foam, cement, asphalt, grass, and mulch. Each of the papers placed on these surfaces was developed using the EDPL before the ESDA(2) and vice versa. The sensitivity test for the ESDA(2) was conducted by processing 10 sheets of stacked paper that were stepped on with the known shoe, beginning with the top sheet. The sensitivity test for the EDPL was conducted by processing 10 sheets of paper stepped on with the known shoe in succession. This study determined the footwear impressions developed using the EDPL were of better comparative value than impressions developed with the ESDA(2). On average, 72.4% of the individual characteristics from the known impression were identified on images developed when the EDPL was used first compared with an average of 38.9% when the ESDA(2) was used first. Therefore, if only one technique is used, the EDPL should be chosen. The sensitivity test determined the ESDA(2) develops high-quality footwear impressions on only the top sheet of paper. No footwear impressions were developed on any sheets under the top sheet of paper. The sensitivity test also determined the EDPL results increase in quality as the amount of dust residue decreases on the surface.     

Lifting Bloody Footwear Impressions Using Alginate Casts Followed by Chemical Enhancement

A method for lifting bloody footwear impressions using alginate casts and enhancing the lifted impressions with amido black is presented. On rough or dark substrates, background interferences may conceal significant details of footwear impressions. Illumination with alternative light sources and chemically enhancing the bloody footwear impressions may reveal additional details, but sometimes, lifting footwear impressions prior to enhancing is the only way to expose hidden details (by using blood reagents not adequate on the original). Several cast formulations were tested for lifting the footwear impressions. The best results were achieved using Aroma fine^®. Enhancement of the footwear impressions was attempted with several reagents prior to lifting, during the casting process, and on the lifted footwear impressions. Applying amido black to footwear impressions lifted with alginate produced the sharpest and most detailed footwear impressions. Alginate castings followed by chemical enhancement with amido black may produce high‐quality footwear impressions for comparison.     

A new method for the recovery and evidential comparison of footwear impressions using 3D structured light scanning

Footwear impressions are one of the most common forms of evidence to be found at a crime scene, and can potentially offer the investigator a wealth of intelligence. Our aim is to highlight a new and improved technique for the recovery of footwear impressions, using three-dimensional structured light scanning. Results from this preliminary study demonstrate that this new approach is non-destructive, safe to use and is fast, reliable and accurate. Further, since this is a digital method, there is also the option of digital comparison between items of footwear and footwear impressions, and an increased ability to share recovered footwear impressions between forensic staff thus speeding up the investigation.     

Assessing the quality of footwear marks recovered from simulated graves

Footwear marks are one of the most frequently encountered evidence types recovered from a crime scene and can provide valuable scene intelligence regarding potential suspects. It has been acknowledged that impressions of footwear and tools can be recovered from graves, but previous studies have only focused on tool mark recovery. This has led to a lack of published information regarding footwear mark recovery from graves. It is therefore important to demonstrate whether the recovery of footwear marks is feasible and, if so, under what conditions this can be achieved. To address recovery, this study, placed 60 three dimensional (3D) impressions of footwear marks within 60 simulated graves. This was done to assess time (1, 2, 4 months) and at known depths (20, 30, 40 cm). The footwear marks within the graves were covered with clothing or left uncovered. The shoe’s design patterns were grouped and counted in a photographic comparison between the 3D footwear impressions, placed within the test-pits, and any recovered impressions. A grading system was adapted by the authors to score the quality of footwear impressions observed during recovery. The results demonstrate that the preservation and recovery of footwear impressions from graves is feasible. The simulated graves covered with clothing showed better preservation of footwear impressions, but there was no clear evidence that time or depth had an effect. The authors note that careful consideration and vigilant excavation skills are needed when excavating graves which may bear potential footwear marks, as their recovery will lead to an increased amount of intelligence that can link suspects to homicide scenes.