垂直抛甩状血迹形态的模拟观察

目的观察不同类型打击工具的垂直抛甩状血迹形态。方法选择常见的菜刀、匕首、方锤、铁管作为打击工具。用沾新鲜鸡血5 m L的工具自上而下进行垂直抛甩,对距离垂直墙壁30 cm处形成的血迹形态进行测量分析,通过对抛甩血迹的整体分布特征(跨度、宽度、密度)、起始血迹的形态特征(长度、宽度、接触角度)进行分析。结果匕首形成抛甩血迹的分布跨度最小(P0.05);在整体分布宽度上,菜刀最小(P0.05);在整体分布密度上,除菜刀与方锤之间差异无统计学意义,其他工具两两之间差异均有统计学意义(P0.05)。方锤较其他三种工具在起始血迹点长度上最长(P0.05);菜刀与方锤、匕首与方锤在起始血迹点宽度上差异有统计学意义(P0.05)。结论每一类型的打击工具所形成的垂直抛甩血迹形态具有一定的特征,可用于命案现场推断打击工具的类型。     

自虐性自杀1例

1案例某女,52岁,某日下午被人发现死于一干枯河河岸边。现场未见明显搏斗痕迹。死者衣着整齐。尸体面东南半侧卧位,左下肢屈曲。距尸体头部30cm处可见一石块(嵌于地面不能移动)上布满血迹及毛发,该石块体部下方有流注状血迹,石块南侧有密集的点状溅落血迹,呈扇形分布,血迹密度越远越稀疏,面积约2m×3m;尸体胸部部位地面可见血泊一处,大小为40cm×40cm,血泊中伴有大量头皮碎屑及毛发;该血泊南侧分布密集的点状溅落血迹,也呈扇形分布,血迹密度越远越稀疏,面积约3m×5m;尸体左上肢下可见一柱状质量约2kg的鹅卵石,各面均有血迹,且分布均匀,其下…     

动脉喷溅血迹动力学及形态学的模拟实验观察

目的观察不同压力、管径对在水平方向上形成的喷溅状血迹的喷射距离及形态的影响。方法建立室内现场环境,利用自制的模拟喷射装置,在60～210mmHg范围内设6种压力,在1.5～4.5mm范围内设4种管径条件,于50、100、150cm 3种高度,制作动脉喷溅血迹。观察水平面上不同喷射高度的喷溅血迹的分布范围、血迹大小及形态特征,并测量其距离,采用SPSS 13.0统计软件进分析,并进行方差检验。结果在不同高度,血液喷射距离随压力增大而增加,随管径增大而减小,两因素间存在交互作用,距离与压力及管径存在较好的线性关系,可得出回归方程。而喷溅血迹的形态特征总体趋势为:高度越高圆形血滴直径约大;管径越粗,边缘毛刺状突起越明显;压力越大,喷射距离越远,且卫星状血迹逐渐增多,拖尾更拉长;随管径的增加,出现椭圆形血滴所需的压力越高。结论动脉喷溅血迹的形态及喷射距离的观察与测量,可用于推断命案现场喷溅源位置及人体受损伤时的体位。     

圆形滴状血迹形态与血滴体积、撞击速度的相关性

目的观察不同体积的血滴以3种撞击速度垂直撞击3种不同介质形成的滴状血迹形态及大小,并探讨其相关性。方法将8种不同体积（14～115IxL）的抗凝猪m形成血滴,以3种不同的撞击速度（3．1～5．4m／s）分别垂直滴落于白纸、玻璃及釉面地砖上,观察形成血迹的形态特征,测量其直径,并采用SPSS13．0统计软件进行分析。结果在3种撞击速度条件下,在3种介质上形成的滴状血迹直径均随血滴体积的增加而增大,血迹直径与血滴体积存在较好的线性关系,可得出回归方程（回归模型R2〉0．85,P〈0．01）;介质表面越粗糙,血迹直径越小;仅在自纸上发现血迹边缘有突起形成,且其数目随血滴体积的增加而增多。撞击速度及血滴体积存在较好的多重线性关系,可得出多重回归方程（回归模型R2〉0．90,P〈0．01）。结论垂直撞击形成的血迹形态及大小与血滴体积、撞击速度具有显著的相关性,可望用于推测出血源位置、受伤体位及出血部位载体。     

血迹分析在现场血迹提取中的应用

对命案现场血迹的研究和分析历来是命案现场勘验及现场分析的重要组成部分。传统上,对现场血迹的研究分析侧重于对血迹形态及其形成过程的分析和研究,通过对现场血迹的分布规律及形态特征的观察和测量,判断血迹来源与形成机制,进而推断血迹与案件或犯罪事实之间的关系和过程[1]。     

不同高度滴落血在3种不同载体上的形态和平均直径

暴力犯罪现场一般都会留下各种血迹,如滴落状、喷溅状、流柱状、擦拭状、抛射状血迹等[1,2],能够反映出血迹形成的方式、受害人出血时的位置、出血后的活动情况以及案件发生过程中其它有价值的信息,据此可以重现犯罪现场所发生事件的过程,在甄别证人证言及犯罪嫌疑人供述等方面有非常重要的意义。本文作者将抗凝人血从不同高度垂直滴落在表面光滑程度不等的物体上,对物体上血迹的形态和大小进行测量和观察,旨在找出垂直滴落血迹的特点及形态变化规律,为分析鉴别刑事案件现场的血迹特征提供实验参考资料。1材料与方法将滴管吸满新鲜的抗凝人…     

血迹形态在命案现场中的应用1例

血迹是凶杀案件中最常见的痕迹物证之一。根据血迹的种类、数量、分布、形态、色泽、检验鉴定和形成方式等综合分析，可以对出血来源，出血部位，受伤时体位，受伤后的活动过程、案件性质、作案地点、作案时间、作案工具、作案人数和作案过程等做出推断，为侦察破案提供依据和证据支持。笔者通过详细的现场勘验，依据现场遗留血迹，分析血迹的形成方式和过程，来解读血迹中包含的犯罪信息。     

水泥地面上滴落状血迹形态的模拟实验

目的观察水泥地面上不同高度、速度对滴落状血迹的形态和大小,应用于现场勘验。方法采用等量抗凝人血,在静态和动态条件下,进行滴落状血迹的模拟实验,观察血迹的形态,测量其直径,用专业统计软件进行分析。结果在静态条件下,滴落状血迹呈圆形,其周围有毛刺状突起;滴落状血迹的大小(直径)与滴落高度之间有较好的线性关系,可得出回归方程。在慢走、急走、跑、快跑动态条件下,滴落状血迹为圆形或椭圆形,沿运动方向的一侧出现突起;高度、速度分别对血迹形态有影响,而且两者有交互作用。结论滴落状血迹形态和大小的观察和测量,可用推断出血部位的高度、运动速度和方向。     

浅谈血迹分类

近年来，命案现场上血迹（bloodstain）的分析已越来越受法医工作者的重视。但是，复习国内外的教材和文献资料，发现存在血迹分类较为笼统、某些概念尚不明晰的问题，比如：将器械作用于有血处所引起的血迹和挥动沾血的器械所产生的血迹一并称之为喷溅状血迹，血掌指印及血足迹缺乏明确的归类等等。所以，实有必要对血迹的分类及其基本概念重新进行审视。为此，笔者斗胆将血迹的分类进行归纳，抛砖引玉，与同行们共同探讨。根据血迹形成的机制不同，结合血迹的形态特点，笔者以为可将血迹分成１０种类型。１喷溅状血迹喷溅状血迹（projecte…     

9种介质上滴落状血迹的模拟实验研究和应用

目的观察不同高度和速度滴落在9种介质上的血迹的形态、大小及与高度,速度之间的关系。方法采用抗凝人血,在静态和动态条件下,进行滴落状血迹的模拟实验,观察血迹的形态,测量其直径,用spss12.0统计软件进行分析。结果在静态条件下,滴落血迹,多呈圆形,其周围有毛刺状突起;7种介质上滴落血迹的大小(直径)与滴落高度之间有较好的线性关系,可得出回归方程。在慢走、急走、跑、快跑动态条件下,滴落血迹为圆形或椭圆形,沿运动方向的一侧出现突起;高度、速度分别对血迹形态有影响,在水泥路面上两者有交互作用。结论滴落状血迹形态和大小,可用于对出血部位的高度、运动速度和方向的推断。     

Automatic Classification of Bloodstain Patterns Caused by Gunshot and Blunt Impact at Various Distances

The forensics discipline of bloodstain pattern analysis plays an important role in crime scene analysis and reconstruction. One reconstruction question is whether the blood has been spattered via gunshot or blunt impact such as beating or stabbing. This paper proposes an automated framework to classify bloodstain spatter patterns generated under controlled conditions into either gunshot or blunt impact classes. Classification is performed using machine learning. The study is performed with 94 blood spatter patterns which are available as public data sets, designs a set of features with possible relevance to classification, and uses the random forests method to rank the most useful features and perform classification. The study shows that classification accuracy decreases with the increasing distance between the target surface collecting the stains and the blood source. Based on the data set used in this study, the model achieves 99% accuracy in classifying spatter patterns at distances of 30 cm, 93% accuracy at distances of 60 cm, and 86% accuracy at distances of 120 cm. Results with 10 additional backspatter patterns also show that the presence of muzzle gases can reduce classification accuracy.     

Changes in the morphology and presumptive chemistry of impact and pooled bloodstain patterns by Lucilia sericata (Meigen) (Diptera: Calliphoridae)

Bloodstain pattern analysis can be critical to accurate crime scene reconstruction. However, bloodstain patterns can be altered in the presence of insects and can confound crime scene reconstruction. To address this problem, we conducted a series of controlled laboratory experiments to investigate the effect of Lucilia sericata (Meigen) on impact bloodstains and pooled bloodstains in association with three combinations of common surfaces (linoleum/painted drywall, wood floor/wallpaper, and carpet/wood paneling). L. sericata fed from the pooled bloodstains and added insect stains through regurgitation and defecation of consumed blood. L. sericata formed defecatory trails of insect stains that indicated directionality. Defecatory stains fluoresced when viewed at 465 nm with an orange filter. These observations differed from Calliphora vicina insect stains because feeding on blood spatter was not observed and trails of insect stains were formed by L. sericata. The fluorescence of defecatory stains can be used as a method to detect insect stains and discriminate them from real bloodstains.     

Quantitative Differentiation of Bloodstain Patterns Resulting from Gunshot and Blunt Force Impacts

Bloodstain pattern analysis (BPA) provides significant evidentiary value in crime scene interpretation and reconstruction. In this work, we develop a quantitative methodology using digital image analysis techniques to differentiate impact bloodstain patterns. The bloodstain patterns were digitally imaged and analyzed using image analysis algorithms. Our analysis of 72 unique bloodstain patterns, comprising more than 490,000 individual droplet stains, indicates that the mean drop size in a gunshot spatter pattern is at most 30% smaller than the mean drop stain size in blunt instrument patterns. In contrast, we demonstrate that the spatial distribution of the droplet stains—their density as a function of position in the pattern—significantly differs between gunshot and blunt instrument patterns, with densities as much as 400% larger for gunshot impacts. Thus, quantitative metrics involving the spatial distribution of droplet stains within a bloodstain pattern can be useful for objective differentiation between blunt instrument and gunshot bloodstain patterns.     

The Reliability of Pattern Classification in Bloodstain Pattern Analysis,Part 1: Bloodstain Patterns on Rigid Non‐absorbent Surfaces

This study was designed to produce the first baseline measure of reliability in bloodstain pattern classification. A panel of experienced bloodstain pattern analysts examined over 400 spatter patterns on three rigid non‐absorbent surfaces. The patterns varied in spatter type and extent. A case summary accompanied each pattern that either contained neutral information, information to suggest the correct pattern (i.e., was positively biasing), or information to suggest an incorrect pattern (i.e., was negatively biasing). Across the variables under examination, 13% of classifications were erroneous. Generally speaking, where the pattern was more difficult to recognize (e.g., limited staining extent or a patterned substrate), analysts became more conservative in their judgment, opting to be inconclusive. Incorrect classifications increased as a function of the negatively biasing contextual information. The implications of the findings for practice are discussed.     

Changes in Attenuated Total Reflection Fourier Transform Infrared Spectra as Blood Dries Out

The time since deposition (TSD) of a bloodstain is a valuable piece of evidence for forensic scientists to determine the time at which a crime took place. The objective of this study was to determine whether attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy could be used to estimate the TSD of a bloodstain in a relatively early period (from 0 min to the time required for the bloodstain to dry out). For this purpose, we used ATR‐FTIR to study the variation in absorbance at certain wavelengths as rat and human blood sample dried out. The absorbance at 3308/cm (A3308) was found to have a close correlation with the TSD during this time period, and the changes in A3308 during the drying of rat and human blood drops under the same controlled conditions showed similar results. The current study indicates that ATR‐FTIR spectroscopy has potential as a tool for estimating TSD at early time periods of blood deposition.     

开发高灵敏度血痕发光试剂用于法医现场检测

目的开发高灵敏度血痕发光试剂用于法医现场检测。方法本项目通过借鉴ECL发光的原理,通过化学电子链的乒乓共轭激活原理,使用均匀设计实验方法优化条件,合成多个新化合物,开发出新型高灵敏度血痕发光试剂。结果本项目开发的高灵敏度血痕发光试剂灵敏度高,发光时间长,在血液稀释1000倍的情况下,使用Chemi Scope3300化学发光成像系统读取荧光值,经过灰度转化最高值达到56,发光时间达到10分钟。结论本项目成功开发了高灵敏度血痕发光试剂,可以应用于法医现场检测。     

Application of Volume‐of‐Fluid Method to Analyze the Viscosity Effect on the Spine Formation of Bloodstains

In bloodstain pattern analysis, the blood droplet volume and surface impact velocity play an important role, and many related experimental studies have been carried out. If an appropriate computational fluid dynamics (CFD) model that could solve bloodstain patterns, especially spine formation bloodstain patterns, can be obtained, the blood droplet volume and impact speeds at various crime scenes can be predicted more accurately. For this purpose, Flow‐3D software using the volume‐of‐fluid method was applied to analyze the behavior of human blood droplets during an impact event, especially focusing on the viscous effect on splashing, which forms the spine which can be used to predict the impact velocity. To obtain a non‐Newtonian viscosity model of blood for a computational fluid dynamic analysis, the venous blood samples of 163 people were tested using a hemorheology instrument. Among the venous blood samples of 163 people, 37 samples for which all blood test results were in a normal range were selected for the non‐Newtonian viscosity modeling. From the CFD analysis, it could be concluded that a non‐Newtonian viscosity model is more appropriate than a constant viscosity model for predicting splashing that forms the spine. The gradient of the non‐Newtonian model at a high shear rate has more of an effect on spine formation than that at a low shear rate. The lowest viscosity with a high velocity at the outer front of the radiating flow plays an important role in forming the splashing pattern.     

An Impact Velocity Device Design for Blood Spatter Pattern Generation with Considerations for High‐Speed Video Analysis,

A mechanical device that uses gravitational and spring compression forces to create spatter patterns of known impact velocities is presented and discussed. The custom‐made device uses either two or four springs (k₁ = 267.8 N/m, k₂ = 535.5 N/m) in parallel to create seventeen reproducible impact velocities between 2.1 and 4.0 m/s. The impactor is held at several known spring extensions using an electromagnet. Trigger inputs to the high‐speed video camera allow the user to control the magnet's release while capturing video footage simultaneously. A polycarbonate base is used to allow for simultaneous monitoring of the side and bottom views of the impact event. Twenty‐four patterns were created across the impact velocity range and analyzed using HemoSpat. Area of origin estimations fell within an acceptable range (ΔX_av = ?5.5 ± 1.9 cm, ΔY_av = ?2.6 ± 2.8 cm, ΔZ_av = +5.5 ± 3.8 cm), supporting distribution analysis for the use in research or bloodstain pattern training. This work provides a framework for those interested in developing a robust impact device.