提取现场足迹的几种方法

足迹是犯罪现场最常见的痕迹物证之一,它不仅能反映出案犯在犯罪现场活动的轨迹,亦或多或少的隐含有犯罪分子的个体信息。现场勘查中,由于案犯的伪装、破坏、技术人员的勘查技能或现场客观条件等因素的制约,现场实际勘验中对足迹的发现、提取和利用往往不尽人意,利用传统的足迹发现和提取方法效果不太理想笔者在实践中发现有几种简单易行的方法,现列述如下:1灰尘减层足迹的提取对承痕体上灰尘层面厚、灰尘细腻且粘附性较强,足迹反映清晰,各种特征反映明显、稳定的,可以直接拍照或利用静电吸附器吸附后再拍照提取。对承痕体上灰尘层面薄,但承…     

闪光灯在拍摄现场足迹中的应用

在现场勘查实践中,经常会遇到遗留在现场各种客体上的灰尘足迹,为了提取到原始的反差好的足迹,我们通常会采取架三脚架打光拍摄、胶带纸粘贴后架空打光拍照、吸附拍照法提取。用这些方法对一般客体虽能取到效果较好的足迹,但对于一些特殊客体就不实用了。笔者尝试用闪光灯对各种客体上遗留的足迹进行直接拍摄提取,在一些案件当中取得了较满意的效果。1拍摄过程1.1器材135单反相机、标准镜头、闪光灯、比例尺。1.2操作方法将留有灰尘足迹的客体用普通现场勘查光源进行观察,直至灰尘足迹轮廓反映清晰,反差最佳,放置比例尺。将照相机的快门速度…     

粉尘地面立体足迹的提取方法

足迹提取是刑事案件现场勘查的主要内容之一,由于承痕客体的复杂性,足迹的显现方法也多种多样.其中,粉尘地面的立体足迹的提取仍是一大难题.粉尘地面立体足迹是指承痕客体表层覆盖了较厚一层质地松软、干燥的粉尘类物质的足迹,如水泥粉、石灰粉或其它类似物质.由于粉尘地面立体足迹的承痕客体的理化性质特殊,不宜采用常规的静电吸附法,用拍照提取和制作石膏模型等方法提取也不理想,因此其提取具有一定的难度.     

短波紫外拍照微弱足迹

我们在勘查各类现场均时常提取到犯罪分子遗留在各种物体上的泥土或灰尘足迹,某些足迹用普通照相法即可得到很好的效果,但也有一些足迹受到承受客体的干扰,或与客体形成反差很小,用普通拍照方法很难得到满意的鉴定效果,本文介绍用短波紫外反射照相方法拍照足迹,可得到较理想的拍照效果。器材和样本春光X——100紫外镜头;美能达XD——700相机(135相机);使用Vv600短波紫外灯;254mm短波紫外滤光片;135黑白胶片或黑白正片(黑白片21°)。装饰板面椅子上穿袜子脚印,包装箱纸壳上足迹拍照方法:将相机装好胶卷,换上春光100紫外镜头,固定好被摄物体,在可见光下对足迹进行调焦然后开启紫外光源,在镜头前面加254mm短波紫外滤光镜,在全黑条件下进行拍照,照射角度可根据可见光照射所观察的情况确定,光圈f5.6,采用系列曝光法,D72显影。因足迹与客体形成的反差极小,用可见光拍不到足迹特征,用短波紫外反射照相拍照清晰地记录下了足迹影像,黑底白色足迹反差很大,并排除了背景的干扰,足迹细微特征反映极明显。     

潮湿、拱形、凹凸不平客体上足痕的提取方法

罪犯作案就要在现场留下明显或不明显的足迹。一般在光滑、平整、干燥客体上的足痕可以用拍照、静电吸附,石膏制模等方法提取。但这些方法对于潮湿、拱形、凹凸不平的客体上加减层足痕的提取,效果不太理想,甚至会失去鉴定条件。笔者多年实践认为,用透明不干胶胶带粘取,悬空透光拍照方法,是最安全、经济可靠的方法,还能补救一些不够鉴定条件的足迹痕迹。     

血痕、泥水足迹与软质客体上加层灰尘足迹的提取

近年来,笔者在勘查现场时,常遇到光滑地面上已干涸的血足迹、泥水足迹,以及软质座垫上灰尘加层足迹,有时对其拍照后将其提取下来,时间短的血足迹和泥水足迹由于未完全干涸较容易提取下来,如果气温高、时间长,足迹会牢固地与地面结合在一起,很难用胶带粘下来,而软质客体上灰尘足迹采用常规方法提取的足迹又易变形,影响检验效果。笔者在实践中摸索到两种简便易行的提取方法,介绍如下:1血痕、泥水足迹的提取准备一条毛巾和一盆热水,将毛巾在水中浸温,稍拧一下,把温热毛巾打开平铺在足迹上,过几分钟后将毛巾移开,使干涸的血迹、泥土潮湿,稍干燥…     

花岗岩地面泥渍或带血足迹的粉末法显现

花岗岩目前是家庭地面装璜的常用材料,现场容易遇到遗留在其上的泥渍和带血足迹。但是拍照、静电吸附、或TMB显血试剂等方法处理都无法提取到理想的足迹。笔者在实际工作中总结出用粉末显     

穿袜足迹形态特征鉴定2例

1案情简介1998年3月15日,鄂州市一住宅区离休干部(女,50岁)被犯罪分子杀死在家中,现场勘查中,在死者卧室油漆地面上遗留有穿袜足迹两枚,系灰尘减层足迹。拍照时,由于地面反光,无法从垂直角度拍到理想照片。后经静电吸附提取拍照,效果较好,同年4月28日晚,该住宅区又发生一起重大入室盗窃案,犯罪分子采取同样入室手段盗窃各种贵重物品价值万余元,现场勘查中,在入口窗户下靠墙的一排方凳上提取穿袜足迹一枚,同时提取了数枚清晰的指掌纹。两案是否同一人所为,笔者对现场足迹进行了检验排查。2检验2.1现场足迹的检验两起案件现场足迹均系犯罪分子…     

残缺立体足迹的拍照方法

在现场勘查实践中,经常遇到面积小、立体感不强的残缺立体足迹.对这类足迹的拍照,如采用标准镜头加接圈的方法,则因拍照距离太短,影响拍照效果;如不加接圈直接拍照,则因成像太小,残缺立体足迹的细微特征无法显示,因而成为刑事照相中的一个难题.通过实践发现,采用中长焦镜头加接圈,再辅以适当的配光进行拍照,则较好地解决了对残缺立体足迹进行拍照这一难题.     

浅谈现场灰尘痕迹的提取

在提取现场灰尘痕迹时可直接拍照，未曾见过有关其他提取方法的报道，而现场灰尘痕迹有的直接拍摄反差微弱无法检验，有的受所处位置、角度等条件的限制，无法直接拍照。在实践中，笔者摸索出一种较为简便有效的方法。既可以加强灰尘痕迹的反差，消除灰尘痕迹背景表面的图案干扰，又能直接提取拍摄，使现场灰尘痕迹的提取利用率有了极大的提高，介绍如下。１适用范围１．１平面上的灰尘加减层手印、足迹应以平滑坚实的平面上的灰尘加减层手印、足迹为主。而且平面承受客体上的灰尘均匀细薄。比如平面上的灰尘减层指印，平面承受客体被细薄灰…     

藻酸盐材料在提取深色织物上潜血足迹的应用

目的建立一种用藻酸盐齿科材料转印显现纺织物上血足迹的方法。方法依据藻酸盐能和纺织物上血足迹中的血结合,从而使足迹被转印到藻酸盐模上,并通过染色增强反差。结果藻酸盐印模材料转印法能够在不破坏织物客体的情况下清楚的反映出血足迹细节特征。结论藻酸盐类齿科材料能够转印、提取显现织物上血足迹,尤其是潜在血足迹,并反映出其细节特征。     

Ultra-trace analysis of illicit drugs from transfer of an electrostatic lift

This article introduces a method of collecting and analysing drug residues that integrates both electrostatic lifting and nanomanipulation-coupled to nanospray ionization mass spectrometry. The application of this hyphenated technique exhibits a useful means of collection and extraction of drug residues with ease and efficiency along with decreased limits of detection. From this method, it will be shown how increased sensitivity of analysis and lower limits of detection for drug analysis can be achieved. The same principles that allow lifting of dust prints by electrostatic lifting can be applied to lifting drug residues. Probing of the drug residues by nanomanipulation occurs directly from the lift, which provides a great platform for extraction. Nanomanipulation-coupled to nanospray ionization-mass spectrometry has been used for the extraction of trace analytes in previous experiments and is known as a very sensitive technique for the detection of ultra-trace residue. This method will demonstrate the electrostatic lifting of drug residue particles from a surface followed by extraction and ionization with nanomanipulation-nanospray ionization. The utility of this novel methodology allows for a more productive analysis when presented with ultra-trace amounts of sample.     

A comparison of the length and width of static inked two-dimensional bare footprints found on a hard compared to a soft surface

In forensic intelligence-gathering it would be useful to evaluate if there are differences between static inked bare footprints captured on hard surfaces compared to soft surfaces. This was undertaken using samples from 30 undergraduate students. Initially a static footprint was taken for each participant on a hard surface and this was followed by a static footprint on a soft surface. On both occasions, the participants stood on an inkless mat and then on reactive paper, creating a two-dimensional print. The Reel method was used to analyse each footprint and the print was measured to see whether a difference existed between length and width (forefoot and rearfoot width) on a hard surface compared to a soft surface. The conclusion from this study was there is a statistically significant increase in length and width of a static bare footprint on a soft surface as opposed to a hard surface. If a forensic footprint examiner compares static bare footprints found on a soft surface and compares them to a static bare footprint of the same foot taken later, then the increase in both length and width of the footprints on a soft surface should be considered in the evaluation.     

鞋内底足迹显现效果的影响因素

目的探究鞋内底足迹的显出情况及可能影响显现效果的因素,寻找有效的鞋内底足迹显现方法。方法收集PU材质的皮鞋鞋垫、EVA材质的运动鞋鞋垫、解放牌胶鞋鞋垫共144只,用多波段光源法、茚二酮法、茚三酮法三种方法分别对穿用时间为一周、一个月、三个月、六个月的鞋内底足迹进行显现,按照显现方法、材质、穿用时间进行分类讨论并对数据进行统计和分析。结果采用多波段光源法、茚二酮法、茚三酮法分别成功显出15、14、19例,有效显出率分别为31.25%、29.17%、39.58%,PU材质、EVA材质、解放牌胶鞋三种材质分别成功显出15、23、10例,有效显出率分别为31.25%、47.92%、20.83%,穿用时间为一周、一个月、三个月、六个月的检材分别成功显出3、6、13、26例,有效显出率分别为8.33%、16.67%、36.11%、72.22%。多波段光源法、茚二酮法、茚三酮法对鞋内底足迹显出率的影响,其差异无明显统计学意义;EVA材质运动鞋鞋内底足迹显出率高于PU材质皮鞋鞋内底足迹显出率,高于解放牌胶鞋鞋内底足迹显出率,并且差异具有统计学意义;穿用时间长的检材显出率高于穿用时间短的检材并且差异具有统计学意义。结论鞋内底足迹的显现效果与鞋内底材质、穿用时间因素有关,多波段光源法、茚二酮法、茚三酮法均能对鞋内底足迹有效显出。     

身高与足迹长度相关关系综合研究

目的全面分析研究足迹长度与身高之间的相关关系及其变化规律。方法在全国范围内大量抽样收集不同地区、不同年龄、不同性别人群的足迹样本,逐一测量其足迹长度,建立数据库,利用计算机进行综合统计、回归分析、比较研究。结果获得大量的分析数据及回归方程。结论足迹长度与身高之间的相关关系明显,可以根据足迹长度分析留痕人的身高。     

Recovery of Trace DNA on Clothing: A Comparison of Mini‐tape Lifting and Three Other Forensic Evidence Collection Techniques

Trace DNA is often found in forensic science investigations. Experience has shown that it is difficult to retrieve a DNA profile when trace DNA is collected from clothing. The aim of this study was to compare four different DNA collection techniques on six different types of clothing in order to determine the best trace DNA recovery method. The classical stain recovery technique using a wet cotton swab was tested against dry swabbing, scraping and a new method, referred to as the mini‐tape lifting technique. Physical contact was simulated with three different “perpetrators” on 18 machine‐washed garments. DNA was collected with the four different DNA recovery methods and subjected to standard PCR‐based DNA profiling. The comparison of STR results showed best results for the mini‐tape lifting and scraping methods independent of the type of clothing. The new mini‐tape lifting technique proved to be an easy and reliable DNA collection method for textiles.     

Gold-plating of Mylar lift films to capitalize on surface enhanced Raman spectroscopy for chemical extraction of drug residues

The method of residue extraction through electrostatic lifting provides a distinctive mode of performing ultra-trace analysis. These lifts provide a medium for analyte extraction via nanomanipulation-coupled to nanospray ionization-mass spectrometry (NSI-MS). This method of extraction can be coupled to Raman spectroscopy for supplemental verification of analytes using surface enhanced Raman scattering (SERS). The gold surface used for SERS provides an enhanced effect on peak signal intensity allowing ultra-trace amounts to be detected more effectively. The aim of this research is to utilize gold-coated films with electrostatic lifting in order to collect latent materials and analyze chemicals of interest contained in them via SERS.     

青年人正常行走左右足底压力分布关系的研究

目的研究左右足底压力分布及变化规律，为利用现场左右足迹分析年龄等人身特点提供科学依据，也为足迹定量化分析与检验奠定基础。方法采用Footscan足底压力步态分析系统，选择30名青年男性，对其正常行走时足底压力分布数据进行采集、处理，运用SPSS12．0统计软件对左右足底6个区域的平均压强进行Pearson相关分析。结果左右足相应区域足底压力分布具有不同程度的相关性。结论正常行走左右足跟区压强相关性最好，在利用现场左右足迹分析年龄等人身特点时，应以跟区特征为主，其它区域特征辅助。     

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 method for impregnating nylon transfer membranes with leucocrystal violet for enhancing and lifting bloody impressions

The objective of this research project was to demonstrate a quick and easy method for impregnating nylon transfer membranes with leucocrystal violet (LCV) for the purpose of lifting and enhancing impressions made in blood. A stamp that would simulate fine detail found in fingerprints or footwear was used to create impressions on a variety of substrates. Four different LCV formulations were tested to determine the effectiveness of the prepared membranes in lifting and enhancing the impressions. Further investigation involved the feasibility of using the LCV membranes in the field by studying the shelf life and storage of the impregnated membranes and the longevity of the lifted impressions. One of the formations studied demonstrated superior lifting and enhancing capabilities, as well as a prolonged shelf life and a resilience of the lifted impressions, thus proving LCV to be an extremely valuable technique.