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。     

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。     

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…     

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。     

二次溅落状血迹形态的模拟实验观察

目的观察二次溅落状血迹的形态特征,探讨其形成机理及与行为方式的关系。方法建立室内现场环境,用10mL血液,以单滴连续滴落或一次性倾倒方式,从10～160 cm高度以10 cm为间隔,制作二次溅落状血迹模型;用棍棒打击及撞击方式制作低位打击及头部撞击溅落血迹模型。观察各种血迹分布,并分析比较其形态差异。结果二次溅落状血迹和头部撞击溅落状血迹在垂直面上均形成倒三角形空白区域的分布形态,但前者分布面积较后者小;低位打击溅落在垂直面上的血迹无此特征,且打击飞溅血滴的飞行角度大于二次溅落血迹。结论利用二次溅落状血迹的形态特征,对于鉴别低位溅血、分析行为方式、证实相关证词具有重要价值。     

命案现场中血痕形态分析与应用2例

１案例资料案例１１９９６年３月某日,受害人左某清晨被人发现死于某火车站围墙内一待用铁轨旁。现场勘查发现,尸体呈仰卧位,头部着地处有较多血迹,与尸体垂直方向１５．８m处的铁路之间,可见有多处片状血迹向尸体方向的拖擦痕。铁路道心在１５cm×２０cm范围内,有散在呈星芒状血迹数１０滴（图１）,从星芒状形态分析,滴落高度应在１m以上。原地对尸体检验：仅在头部检见多处类圆形损伤,颈部被锐器切割深达颈椎骨,右颈总动脉、颈内静脉被切断;在尸体损伤处可见血痕呈流柱状垂直滴落于地面,形成血泊。经对颈右侧部、头部血痕形状…     

多次砍击颅骨自杀法医学检验分析1例

正1案例资料简要案情王某,女,57岁。某日中午在自家卧室内被家人发现受伤,后送医院抢救无效死亡。现场为一农家院落。煤房煤堆处见滴落血迹,煤堆下地面有20cm×30cm血泊。墙面及周围堆积物处见多处喷溅、挥溅状血迹,最低处距地面90cm。煤房至客厅间地面见5处滴落状血迹,客厅、卧室门框及把手处见擦蹭血迹。客厅内仅见少许稀释血迹印痕。上述现场在案发后均被其家人进行过较大程度地清扫和     

自伤后缢死的法医学鉴定分析1例

<正>1案例资料1.1简要案情及现场勘查2009年8月28日上午6时50分,某公园发现1具尸体。中心现场位于平台上,平台东端南侧景观石(高150cm、宽90cm、厚60cm)北距地面90cm高处突起部位上有流柱状血迹,周围有溅落血迹,其下方有大量流柱状血迹,周围有多量向下溅落血迹,两血迹之间有上下方向擦拭状血迹;北侧景观石(高60cm、     

特殊方式自杀1例

正1案例资料1.1简要案情及现场勘查杨某,男,39岁,独居。2013年某日被发现死于其租房内。租房门窗完好,门上卡巴锁完好,处于锁闭状态。室内物品摆放较整齐。现场地面、墙、杂物等处分布多种形态血迹。室内北侧为一简易木床,死者呈左侧卧位,头位于床板下,上半身裹有多条棉被。左手食指套有一剪刀。门口桌子上见1把带血菜刀。棉被、地面见多处血泊。靠近门口地面上见多处滴落状血迹和擦拭状血迹。靠近门口地面杂物上见多处喷溅状血迹。除死者足迹外无明显他人足迹。现场     

1例自伤后冻死法医学勘验分析

2003年12月14日8时许,在本市一河滩发现一具女尸(陆某女,18岁,某学院在校大学生)。1现场勘验中心现场位于茵香河入渭河口西侧的高新大道北侧路基上,在距路基北沿2m和2.5m有两处50cm×40cm、60cm×40cm片状血迹,周边5m×7m范围的散在点状血迹。南侧血迹成血泊,地面渗血深,中西侧有一块沾有血迹和毛发的整块砖,中东侧有一副沾血眼镜(镜片内侧血量较大),左侧镜架向内弯曲。血泊内见发辫及橡皮筋压痕,血泊周边大量滴落血点。北侧血迹呈低位滴落血,周边多处滴落血点,其中路基边沿、路基肩的小石块北侧面上有多处滴落血点;路基斜坡中部砖块面上见…     

Relative effects of posture and activity on human height estimation from surveillance footage

Height estimations based on security camera footage are often requested by law enforcement authorities. While valid and reliable techniques have been established to determine vertical distances from video frames, there is a discrepancy between a person's true static height and their height as measured when assuming different postures or when in motion (e.g., walking). The aim of the research presented in this report was to accurately record the height of subjects as they performed a variety of activities typically observed in security camera footage and compare results to height recorded using a standard height measuring device. Forty-six able bodied adults participated in this study and were recorded using a 3D motion analysis system while performing eight different tasks. Height measurements captured using the 3D motion analysis system were compared to static height measurements in order to determine relative differences. It is anticipated that results presented in this report can be used by forensic image analysis experts as a basis for correcting height estimations of people captured on surveillance footage.     

基于紫外可见积分球反射光谱法鉴定血痕经历时间

目的建立一种快速鉴定血痕陈旧度的方法。方法在实验室条件(20℃、25℃、30℃)下,使用UV-2450型紫外可见分光光度计,利用反射附件ISR-240A积分球,以BaSO_4标准白板做参比,间隔一定时间测定健康人耳静脉血血痕纱布的反射光谱,采集特定波长反射率R_(541)、R_(577),计算R_(541)/R_(577)值,使用SPSS 17.0软件进行直线拟合与回归分析。结果一定条件下8 h内,血痕经历时间与其特定波长紫外可见反射率比值回归分析的R~2均大于0.8,回归方程成立,血痕经历时间与R_(541)/R_(577)值具有高度相关性。结论所建立的方法简便、快速、无损,可靠性好,可以对实验室条件下8 h内血痕经历时间进行鉴别。     

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.     

Fatal falls from a height: two case studies

Two case studies are presented involving fatal falls of adult females from a height. One involved a launch at low speed from a balcony, and one involved a launch at high speed from the top of a cliff. Crime scene evidence obtained on the balcony itself provided a strong indication of homicide, but subsequent investigation showed that the fall was accidental. No crime scene evidence was obtained for the cliff fall since the fall initially appeared to be just another suicide from a popular suicide spot. Subsequent investigations indicated homicide based on measurements of cliff height, horizontal distance to the impact, and available runup distance, plus measurements of possible run, jump, and throw speeds. It was found that a female weighing 61 kg (134 lb) can be thrown at speeds up to 4.85 m/s by a strong male, more than enough to account for the estimated launch speed (4.5 m/s). Given the available 4.0 m runup distance, it was found that women of better than average rather than elite athletic ability can dive at speeds of about 3.5 m/s or jump feet first at speeds of about 4.0 m/s, both being less than the estimated launch speed. The decedent had no athletic ability and landed head first after falling through a height of 29 m.     

应用单细胞凝胶电泳测定人血痕淋巴细胞降解的实验研究

目的探讨血痕形成时间与其DNA降解的淋巴细胞出现率的关系。方法应用单细胞凝胶电泳(SCGE)技术结合荧光显微镜和专业的计算机图像分析技术,测定离体72h内不同时间段的血痕中彗星样淋巴细胞出现率。结果获得人离体血液经不同放置时间间隔后,经LUC IA图像分析系统采集得到荧光图像,并获得体现DNA降解趋势的二项式回归方程y=-0.0178X2+2.4623X+8.1098,r2=0.9522,具有高度的统计学意义。结论72h内的人血DNA降解的淋巴细胞出现率与血痕形成时间之间具有高度的线性相关。     

Fundamental studies of bloodstain formation and characteristics

A detailed understanding of blood droplet impact dynamics and stain formation is an essential prerequisite to the interpretation of both individual bloodstains and spatter patterns. The current literature on theoretical models for the spreading and splashing of liquid drops on surfaces relevant to the forensic context of bloodstain formation has been reviewed. These models have been evaluated for a paper substrate using experimental data obtained as function of droplet size, impact velocity and angle. It is shown that for perpendicular impact there are fairly simple mathematical models for the spreading diameter and the number of scallops or spines formed around the stain though these have quite limited ranges of validity in their basic form. In particular, predictions for the diameter are best for small droplets impacting at high velocity and the number of spines saturates for higher impact velocities. In the case of spreading, a modification to the energy conservation model is found to provide excellent agreement with experimental stain diameters across a wide range of impact velocities. For non-perpendicular impact, the width of stains is found to depend principally on the normal component of impact velocity and may be predicted by an appropriate modification to the expression for the perpendicular case. Limitations in the calculation of impact angle from the stain aspect ratio are identified and a theoretical basis for the prediction of spines around an elliptical stain is proposed. Some key issues for future research are identified which include a systematic, quantitative study of the effect of surface properties on bloodstain formation.