Inter-observer error for area of origin analysis using FARO Zone 3D

In a bloodletting incident, the area of origin (AO) of an impact bloodstain pattern is crucial when establishing the sequence of events. The use of laser scanners and other three-dimensional (3D) technologies to document and analyse bloodstains have been the subject of previous papers, especially where AO analysis is concerned. FARO Zone 3D (FZ3D) is a relatively new software programme that can be used for bloodstain AO analysis. FZ3D requires a greater understanding of inter-observer errors associated with AO. This study looked at the inter-observer variation between 21 examiners when repeatedly calculating the AO six times for a single impact pattern on a plain white wall. An impact rig which consisted of a spring tension arm was positioned and fixed 45 cm from the X wall (right wall), and 45 cm from the Y wall (left wall). This experimental design resembles an impact blow for a bloodletting event. The AO was unknown to all examiners, making it a blind study. The collected results were documented in a Microsoft Excel datasheet and later analysed. From previous literature, a 30 cm acceptable allowance was utilised for AO analysis; however, there is currently no accepted standard error for this type of analysis. The overall total 3D mean error for all examiners was 5.62 cm. The maximum error for any one impact analysis was 24.27 cm. The variation of the data, which was collected by all examiners, was documented as X = 1.14 cm, Y = 1.24 cm, Z = 1.68 cm, and the total 3D error = 2.28 cm. The total 3D error for any one examiner and the variance between examiners did not exceed the 30 cm acceptable allowance utilised in previous literature.     

On the discrimination between facial creams of different brands using Raman Spectroscopy and partial least squares discriminant analysis for forensic application

Determining the origin of cosmetic traces is an important aspect of forensic investigations, that helps linking a suspect to a crime. Such type of evidence can help further narrow down the undergoing investigations. This paper reports the first use of Raman Spectroscopy (RS) coupled with the exploratory principal component analysis (PCA) and supervised partial least squares-discriminant analysis (PLS-DA) in facial creams. 40 facial cream samples of 8 different brands were studied in this work. Preliminary assessments through visual inspection of their Raman spectra revealed the presence of oxides, titanium dioxide, castor seed oil, and beeswax. Also, the peaks of alkyne groups were indicative of the presence of talc or mica compounds. The exploratory PCA correctly segregated the samples into 8 clusters and the supervised PLS-DA model correctly classified them into 8 classes. Further evaluation of the performance of the trained PLS-DA model resulted in perfect classification shown by the receiver operating characteristic (ROC) curves. The PLS-DA model also resulted in 100% accuracy of correctly assigning the brand on the face wipes on each of the five substrates viz. cotton, dry and wet tissue paper, nylon substrate, and polyester. This validation was done treating these samples as unknowns. The study has a potential for use under actual forensic casework conditions.     

Three‐Dimensional Comparative Analysis of Bitemarks*

Abstract: Historically, the inability to accurately represent bitemarks and other wound patterns has limited their evidentiary value. The development of the ABFO #2 scale by Krauss and Hyzer enabled forensic odontologists to correct for most photographic plane distortions. The technique presented here uses the ABFO #2 scale in conjunction with the evolving technologies of laser scanners and comparative software commonly used by the automobile industry for three‐dimensional (3D) analysis. The 3D software comparison was performed in which measurements were analyzed of the normal distance for each point on the teeth relative to the bitemarks. It created a color‐mapped display of the bitemark model, with the color indicating the deviation at each point. There was a correlation between the bitemark and the original teeth.     

Direct identification of various copper phthalocyanine pigments in automotive paints and paint smears by laser desorption ionization mass spectrometry

Direct identification of copper phthalocyanine (CuPc) and chlorinated CuPcs in paints for discrimination between blue automobile paints by means of laser desorption mass spectrometry (LDMS) in the absence of a matrix is reported. The models consisted of eight commercially available CuPc pigments applied to a piece of plain white coating paper. The relationship between the peak intensity at m/z 575 of the CuPc, the number of pulsed laser shots, and laser power was compared to optimize laser abrasion. LDMS analysis of the model paints demonstrated that all characteristic components of the CuPc pigments in the paint films were in good agreement with those in the powder pigments. Further, the chlorinated CuPcs in the paint films could be distinguished. A quantity of 42 blue paint films, representing the paints used for painting Japanese domestic trucks, was examined by LDMS analysis. Results indicate that the paints can be classified into four categories based on the chlorinated CuPc components of the paints. Therefore, LDMS spectra of CuPc pigments would be useful for the identification of paints in forensic investigations. Herein, we report the successful identification of the CuPcs in a paint smear on the frame of a bicycle damaged in a hit-and-run accident, using the LDMS spectra.     

Determination of the Chronological Order of a Laser Printing and Gel Pen Writing Without any Crossing Strokes

Laser printers and writing instruments are being exploited by the forgers to produce fabricated documents. They often produce such documents by appending genuine signature on a blank sheet and later printing on it. Often these fabricated documents do not contain intersection of strokes and may pose a difficulty to forensic document examiners in analyzing cases related to such documents. Keeping in mind the limited research work done on nonintersecting strokes, the present study has been conducted with an aim to determine the sequence of nonintersecting strokes of gel pens and laser printers. Three hundred samples of nonintersecting strokes of gel pen ink and laser printing were prepared. Of these 300, 150 had laser-printed text below the gel pen strokes and the remaining 150 were prepared with gel pen stokes below the laser-printed text. The samples have been analyzed using Nikon SMZ 800N stereomicroscope. Three micro-conformation features, that is, pattern of toner distribution, ink distribution, and fiber distribution have been observed in the samples. The results demonstrate the successful establishment of sequence of nonintersecting strokes in case of gel pen and laser-printed documents by the determination of micro-conformation features.     

激光雕刻印章印文真伪鉴定

激光雕刻印章是当代科技集激光技术、计算机技术、数控技术、电子技术等为一体的刻印技术,已广泛应用于社会。激光雕刻印章印文真伪鉴定成为文检员面临的新课题。本文从激光雕刻印章的原理及程序、印章印文的特点、印章印文的检验方法、鉴定时可使用的特征、形成非本质差异的原因等方面进行了探讨与研究。     

电针结合激光治疗单纯性肥胖30例

目的 比较电针结合激光与单纯电针治疗单纯性肥胖的疗效差异。方法 将60例单纯性肥胖患者随机分为治疗组(电针结合激光治疗)、对照组(电针治疗)各30例,分别观察两组治疗前后体质量、腰围、臀围、股围、体质量指数（body mass index, BMI）的变化。结果 治疗后两组患者的体质量、腰围、臀围、股围、BMI均显著下降(P<0.01);治疗组体质量、腰围治疗前后差值显著大于对照组(P<0.05,或P<0.01),两组减肥疗效比较,差异无统计学意义（P>0.05）。结论 电针结合激光与单纯电针均对单纯性肥胖具有确切的临床疗效,电针结合激光在减少患者腰围上具有独特优势。     

An evaluation of measurement uncertainty of trajectory angles using a 3D laser scanner

Measuring trajectory angles of bullet defects at a crime scene is an important part of crime scene investigation as these angles can be used for shooting incident reconstructions. The Washington State Patrol Crime Scene Response Team (WSP CSRT) had a desire to report and use measured trajectory angles. To report quantitative measurements, a statement of uncertainty for the measurement must also be reported due to an accreditation requirement through the ANSI National Accreditation Board (ANAB), through which the WSP CSRT is accredited. This evaluation examined the measurement uncertainty of the 3D laser scanning method that the WSP CSRT utilizes for measuring the vertical and azimuth angles from trajectory rods fitted to bullet defects. Three studies were performed which examined the variation of vertical and azimuth angle measurements from trajectory rods on flat surfaces, the variation of azimuth angle measurements from a trajectory rod on a curved surface, and a traceability study with known vertical and azimuth angle measurements. Seven common substrates were selected as target materials and were shot with 9 mm Luger and 0.45 Auto caliber bullets. A vehicle with one bullet defect was utilized for the curved surface study. The WSP's current fleet of Trimble X7 3D laser scanners, the WSP Criminal Investigation Division (CID) Detectives who operate these scanners, and the Forensic Scientists responsible for trajectory rod placement and angle measurements were utilized. An overall measurement uncertainty of +/− 2.6 degrees at an approximate 95% confidence interval was determined for all trajectory angles measured from trajectory rods.     

莫达非尼药片的激光共聚焦显微拉曼光谱快速检验

目的建立莫达非尼药片的拉曼光谱快速定性检验方法。方法莫达非尼对照品和药片检材分别研磨后经拉曼光谱检验得到拉曼谱图。结果经比较,二者图谱一致,确定检出莫达非尼成分,结果可靠。结论莫达非尼药片在本文所述的条件下有较好的响应,峰型较好,峰位准确,同时药片中的淀粉等物质干扰较小。本文所建立的拉曼光谱检验方法,简便、高效、准确,可供一线执法、检验部门对查获的莫达非尼药片进行快速的定性检验。     

Human height estimation from highly distorted surveillance image

Video surveillance camera (VSC) is an important source of information during investigations especially if used as a tool for the extraction of verified and reliable forensic measurements. In this study, some aspects of human height extraction from VSC video frames are analyzed with the aim of identifying and mitigating error sources that can strongly affect the measurement. More specifically, those introduced by lens distortion are present in wide-field-of-view lens such as VSCs. A weak model, which is not able to properly describe and correct the lens distortion, could introduce systematic errors. This study focuses on the aspect of camera calibration to verify human height extraction by Amped FIVE software, which is adopted by the Forensic science laboratories of Carabinieri Force (RaCIS), Italy. A stable and reliable approach of camera calibration is needed since investigators have to deal with different cameras while inspecting the crime scene. The performance of the software in correcting distorted images is compared with a technique of single view self-calibration. Both approaches were applied to several frames acquired by a fish-eye camera and then measuring the height of five different people. Moreover, two actual cases, both characterized by common low-resolution and distorted images, were also analyzed. The height of four known persons was measured and used as reference value for validation. Results show no significant difference between the two calibration approaches working with fish-eye camera in test field, while evidence of differences was found in the measurement on the actual cases.