Improving the point of origin determination in bloodstain pattern analysis

In bloodstain pattern analysis, it is important to know the point of origin (PO) of an impact pattern. This point can be estimated by means of the stringing method, the tangent method, or by commercially available computer programs. In this study, the accuracy of two computer programs was investigated under different conditions. Impact patterns were created by means of a modified mouse trap, and subsequently the PO was calculated. By examining the characteristics of single bloodstains, the influence on the deviation could be determined. To improve the estimation of the PO, it is important to select bloodstains that lie close to the presumable location of the blood source, that are large (width >1.5 mm) and that show an elliptical form. If possible, bloodstains from different walls should be taken into account. Our recommendations may improve the PO determination of impact patterns.     

Effects of CBRN Decontaminants in Common use by First Responders on the Recovery of Latent Fingerprints—Assessment of the Loss of Ridge Detail on Glass

Following a CBRN incident, first responders use decontamination procedures to reduce the risk of exposure. The effect of decontamination on forensic trace material has, however, not been fully examined. This study sought to evaluate the effect of five different physical or chemical decontamination materials on the recovery of latent fingerprints. Fingerprints were deposited on glass slides, decontaminated, and assessed on the presence of ridge detail. The results demonstrate that decontamination affects the quality of latent fingerprints substantially. On at least 61% of the fingerprints, a reduced amount of ridge detail was observed upon decontamination. Furthermore, development with cyanoacrylate appeared not to succeed anymore. Instead, the ability of vacuum metal deposition to successfully develop decontaminated fingerprints is demonstrated. The results from this study may contribute to an increased forensic awareness regarding decontamination and emphasize the necessity for further research into new item decontamination procedures or new forensic initiatives prior to decontamination.     

The Liberal Value of Privacy

This paper presents an argument for the value of privacy that is based on a purely negative concept of freedom only. I show that privacy invasions may decrease a person’s negative freedom as well as a person’s knowledge about the negative freedom she possesses. I argue that not only invasions that lead to actual interference, but also invasions that lead to potential interference (many cases of identity theft) constitute actual harm to the invadee’s liberty interests, and I critically examine the courts’ reliance on a principle of ‘no harm, no foul’ in recent data breach cases. Using a number of insights from the psychology of human belief, I also show that the liberal claim for protection of privacy is strengthened by the observation that often the privacy invader cannot be held responsible for the influence on the invadee’s negative freedom.     

Social Science and the Public Interest

Social Science and the Public Interest

Social Science and the Public Interest January/February 2012     

Volume Determination of Fresh and Dried Bloodstains by Means of Optical Coherence Tomography

The volume of bloodstains found on crime scenes may help forensic investigators reconstruct the location and kinematics of bloodletting events, as stain size, volume, and impact velocity are related. Optical coherence tomography was used as a method to determine the volume and volume ratio of dried and fresh bloodstains on both glass and irregular surfaces or deposited with an impact velocity. The volume of blood drops deposited on smooth glass surfaces was measured within a deviation of 2%. This deviation increased for droplets on irregular surfaces or deposited with an impact velocity. The volume ratio of dried and fresh bloodstains was equal to 19–28% depending on the individual donor and on the use of an anticoagulant. Optical coherence tomography is a good method to determine the volume of fresh and dried bloodstains in laboratory conditions and allows accurate determination of the dry/fresh ratio.     

基于纤维二次转移确定纤维屑作为示踪物质的探讨

目的 考察纤维屑在涉及二次转移案件中作为示踪物质的适用性.方法 根据一个实际案例展开,在该案中,犯罪嫌疑人涉嫌多起入室盗窃案.纤维开始分散于嫌疑人所用车辆,后被嫌疑人“携带”并分散到犯罪现场,最终这些纤维在勘查过程中被收集.设计完善了一个可用于散布纤维的便携式装置,并完成了一系列二次转移的相关实验.结果 设计的装置可在短时间均相的散布纤维,单次接触不能全部转移第一表面的纤维碎屑.只有1-15％的纤维会转移到代表犯罪现场的第三表面.实际转移的纤维数与包括比如表面的材质在内的各种因素都有关系.结论 在所选参数范围内,相对大量的纤维有可能转移到犯罪现场并在现场勘查过程中被提取.     

Did Covid-19 Change Armed Group Governance? Evidence from a Survey of Local Security Authorities in Colombia

As the Covid-19 pandemic began, initial reports suggested that armed groups would seize the opportunity to expand their control over territory and civilians. However, drawing on an original survey of local security officials responsible for monitoring armed group behaviour in Colombia, we find little evidence of significant shifts in the presence or behaviour of political or criminal groups. Contrary to prevailing expectations, we also find that armed group governance is common in areas contested by multiple groups. Our findings shed new light on armed group adaptation to shocks, and challenge the assumption that territorial control is a prerequisite for governance.