碘热升华喷枪显现潜手印的应用研究

本文提出一种以石英灯为加热器的碘热升华喷枪显现潜手印的新方法。实验表明,该技术方法操作简便,适用范围广,手印显出率高,尤其是显现遗留在墙面、本色铝合金表面、UPVC表面的潜手印效果明显。     

33.15及33.6探针对中国人DNA指纹图的研究

目的统计用33．15及33．6探针对中国人进行DNA指纹图检验的群体调查资料，为实际案件的检验提供理论依据。方法应用33．15及33．6探针为中国北京地区无关群体的血液进行DNA指纹图分析。结果应用33．15探针检验15人的DNA指纹图，无关个体间相关机率为1．03×10-15，两无关个体间出现同一谱带的平均概率0．176；应用33．6探针检验19人的DNA指纹图，无关个体间相关机率为1．53×11-11，两无关个体间出现同一港带的平均概率为0．187；两探针均符合孟德尔遗传规律，均具有组织同一性。结论本研究结果可应用于法医物证检验的亲子鉴定及个体识别。     

Lip print enhancement: review

Lip print(LP)evidence can be an essential tool for human forensics.LPs have conventionally been developed using substances such as lysochrome dyes,fluorescent dyes,indigo dye,aluminium powder,and silver metallic powder.However,techniques for LP enhancement from various substrates are currently inconsistent and lack standardisation in practice.This review summarises current knowledge on the physical and chemical techniques of LP enhancement,identifies limitations,and provides suggestions for future research on practical applications of cheiloscopy as a forensic tool in criminal justice.     

Problems in identifying work from print wheel typewriters

A recent development in typewriters and word processors is the print wheel printer, a machine that has become a significant factor in current office machine production. With this unit typefaces are mounted on spokes projecting from a central wheel. These machines produce high quality work with limited individuality. The mode of identification is significantly different from the work of a typeball machine and in some respects from the earlier typebar typewriters. Thus it is important to distinguish between the work of print wheel machines and other classes of typewriters. Consideration is given to individual identifying characteristics; the effect of the machine's ability to produce justified or flush right margins; and the general limitations on their identification.     

The recovery of finger marks from soot-covered glass fire debris.

This study aimed to expand the scope of previous research by assessing the effectiveness of soot-removal techniques on glass from petrol-bomb debris using methods of 1% and 2% sodium hydroxide (NaOH) solutions, ultrasonic bath and vacuum suction. Of particular interest were the 1% and 2% NaOH solutions applied to the soot-covered surfaces. Petrol bombs containing petrol or a 50:50 mix of petrol and motor oil were exploded and the debris was collected for analysis. Favourable results were found to varying degrees using each of the soot-removal methods with the 1% and 2% NaOH wash solutions, being the most useful. The 2% NaOH solution also proved successful as a soak to loosen and remove heavy contamination of soot and accelerants without damaging the finger mark beneath. This study also found that recovery of finger marks in blood from beneath soot using the 2% NaOH solution was possible. Finger marks were also applied to glass bottles with plastic adhesive labels, and providing the fire damage is not too great marks were also retrievable. Results from this study lead to the conclusion that the NaOH wash solution is ideally suited for soot removal to reveal latent and blood-contaminated marks both within the laboratory and at crime scenes.     

同源激光雕刻橡塑印章印文的鉴别方法

目的找出同源激光雕刻橡塑印章印文之间的特征差异,建立检验鉴定此类印章印文的鉴别方法。方法制作14枚同源激光雕刻橡塑印章,借助文件仪、显微数字分析仪等仪器观察分析其盖印的印文样本。结果找出了各种细节特征差异。结论同源性激光雕刻橡塑印章因其规格性特征符合很好,检验鉴定要以细节特征比对为主。     

Perceptions of blind proficiency testing among latent print examiners

In recent years, scholars have levied multiple criticisms against traditional proficiency testing procedures in forensic laboratories. Consequently, on several occasions, authorities have formally recommended that laboratories implement blind proficiency testing procedures. Implementation has been slow, but laboratory management has increasingly expressed interest in initiating blind testing in at least some forensic disciplines, with some laboratories conducting blind testing in almost all disciplines. However, little is known about how a key population perceives blind proficiency testing, i.e., forensic examiners. We surveyed active latent print examiners (N = 338) to explore perceptions of blind proficiency testing and determine whether beliefs varied between examiners who work for laboratories with and without blind proficiency testing. Results suggest that examiners do not hold particularly strong beliefs about such procedures, but that examiners who work in laboratories with blind proficiency testing procedures view them significantly more positively than those who do not. Further, examiner responses provide insight into potential obstacles to continued implementation.     

The effect of electron beam irradiation on forensic evidence. 1. Latent print recovery on porous and non-porous surfaces

The recent use of the postal system as a means of delivering anthrax spores via several contaminated envelopes has led to the selective irradiation of mail. These as yet unsolved attacks and the U.S. Postal Service's decision to irradiate certain types of mail has led to some unexpected complications. The high doses of radiation required to destroy biological agents like anthrax are sufficient to induce damage to other materials present in the envelope. There have been reports of damage to many different items that have been subjected to irradiation, including paper, precious gems, plastic, computer discs, and electronics. However, few studies have examined the effect of such treatments on items of forensic interest. In this paper, the authors focused on the impact of the irradiation process on the ability to visualize latent prints. This experiment involved using several donors, substrates (both porous and non-porous), and visualization reagents. The results indicate that the irradiation process can have a detrimental effect on the success of certain visualization reagents.     

Shoe print examinations: effects of expectation, complexity and experience

Even though trace evidence is becoming more and more important in legal cases, only little is known about the influence of task and context factors on comparative judgments. In the present study we investigated how expectations and complexity affect shoe print examinations and to what extent differences exist between beginners and experienced examiners. Twelve examiners assessed similarity between a shoe print and a shoe for eight different cases. For half the cases expectation was induced by providing additional incriminating evidence. A complex case meant that the print was relatively noisy, for example because the perpetrator rotated his foot. A simple case meant that the print was clear. The results showed that there was no effect of expectation and no effect of experience. Only complexity affected the examiners' assessments: when the background was noisy, the acquired features received a lower evidential value than when the background was clear. Apparently, examiners compensated for the quality of the print and were more cautious in drawing conclusions when prints were less clear. Even though the results allow for some optimism with regard to the influence of expectations on shoe print examinations, it has to be taken into account that the Dutch procedure is supported by a formal guideline, which may (partly) explain the present findings.     

A methodology for finger mark research

Currently there is no standard way of carrying out research into finger mark enhancement techniques. Individuals, groups or establishments tend to use different methodologies depending on a number of factors, especially finance and time. However, data published in the literature can be misleading to the forensic community if the data generated reflects research involving very few finger marks or if those finger marks have been deliberately doped with an unnatural balance of sweat or an unusual contaminant. This paper presents an experimental methodology which is intended to establish minimum standards for those carrying out finger mark enhancement research (at least within the United Kingdom) and bring some consistency to the process. It will aim to identify the many variables encountered when dealing with finger marks and suggest experimental methods to take these into account. It will also present the key stages of the progression of a process from a laboratory concept to a tool used on operational work.     

Semen analysis using methods of molecular genetics--a case report

The presented case report describes the exclusion of the suspect of a sexual offence by means of methods of molecular genetics. Pretests for prostate-specific antigen performed at the beginning of the investigation and cytological sperm tests were negative. Nevertheless, by combining the methods of differential lysis and DNA quantification a small number of spermatozoa could be demonstrated in the trace evidence. Subsequently, the profile of the woman's boyfriend, with whom she had had unprotected vaginal intercourse two days before the incident, could be detected in the fraction of the hard lysis.     

An examination of gender and age in print media accounts of child abductions

Previous research has suggested that the print media over-report on certain demographics of abducted children. Specifically, cases where the abduction victim is younger or the abduction victim is female are most often covered. The purpose of the current study was to systematically examine, through the research technique of content analysis, whether a lack of congruency exists between newspaper articles detailing child abduction victims and empirical data of the same. Newspaper articles were collected from LexisNexis Academic, and empirical data were drawn from the Second National Incidence Studies of Missing, Abducted, Runaway, and Thrownaway Children. The results revealed that gender and age play only a minor role in deciding which abduction incidents are covered by newspapers, as well as the extent to which they are reported on. Specifically, newspapers dedicated more words to female victims than male victims and reported more on younger children (aged 11 and under) than older children (aged 12 and over) when they were the victim of a nonfamily abduction. It appears, however, that in all other types of abduction cases, newspapers are reporting a rather factual depiction of the demographics of victims. The implications of these findings are discussed.     

The Stability of Prostate-Specific Antigen in Semen Under Various Temperatures

Prostate-specific antigen (PSA) is most commonly used for identifying semen, especially in the absence of sperm. However, PSA concentration varies according to storage temperature and duration, and little is known about its stability in semen. This study was therefore aimed to determine the stability under five different temperatures: −80, −20, 4, 25, and 37°C; and nine different durations: 1, 2, 3, 5, 7, 14, 30, 90, and 180 days. All samples were stored at −80°C after being secreted from the volunteers' body until analyzed. Results showed that the PSA concentration declined significantly over time under all temperatures studied except −80°C. At −20 and 4°C, PSA was still detectable on Day 180 with 50% and 70% decrease from its original concentration, respectively. At 25 and 37°C, PSA was detected up to Day 7 and 3, respectively. This information might assist forensic scientists understand more about PSA nature and integrate it into their works.     

Estimating actual foot size from a static bare foot print in a White British Population

In forensic intelligence-gathering it would be useful to be able to estimate the size of a perpetrator's foot from a standing bare footprint found at the scene of crime. Currently, the advice is to add a fixed amount to the length of the footprint (typically 1.5 or 2.0 cm), but there is little evidence for this approach. This study used measured footprint and actual foot lengths from 146 participants from the white British student population of a University in the UK. Data were analysed using multiple regression with foot length as the dependent (outcome) variable and footprint length and sex as the independent variable/factor respectively. Sex was not a significant predictor. The regression equation for the best estimate of the foot length is 19.89 + 0.95 × print length ± 8 mm.     

The influence of polymer type, print donor and age on the quality of fingerprints developed on plastic substrates using vacuum metal deposition.

This study investigated fingerprint development on five different polymer substrates using vacuum metal deposition (VMD). The conditions required for optimum development are shown to depend on a number of factors. No one set of conditions will result in good development in all situations. Polymer type has been confirmed as a major factor in determining the types of development that will occur and the optimum VMD conditions required. For more consistently successful VMD development, polymer type should be determined before selecting conditions. While polymer type is a key factor in determining optimum development conditions, there may be variation of the optimum conditions within a polymer type, most likely due to the presence of additives in the plastic. The heaviness of a latent print, i.e. amount of residue that constitutes the print, also affects the VMD conditions required. The donor, manner of deposition, and age of a print affect the heaviness of the deposit. The heavier the print, the higher the gold count necessary for successful VMD development. The occurrence of 'empty prints' (i.e. zinc deposition on the general background but not on or between the print ridges) was found to be related to polymer type and print heaviness. Heavy prints on PVC and PET are the most likely to be 'empty' after VMD treatment. The development of empty prints may be due to the diffusion of print residue into the print valleys. Pre-treatment with cyanoacrylate fuming was also found to affect VMD development. In particular, it was shown that cyanoacrylate pre-treatment was beneficial for print development on PET and PVC. The results of this study were used to formulate guidelines for use as an aid by laboratories using VMD in casework.     

A Study of Leucine Aminopeptidase as a Possible Means of Identifying Semen

Leucine aminopeptidase (LAP) activity was investigated in a number of human body fluids, vegetable extracts, casework stains and vaginal swabs by means of either a spot test or photometric assay. The vaginal swabs were also examined for acid phosphatase (AP) and the levels of activity of both enzymes were compared. The results show that LAP can be readily detected in semen stains by means of the spot test or photometric assay. The spot test for LAP was found to be slower and less sensitive than the widely used AP test although no positive reactions were obtained with semen-free vaginal swabs. None of the other body fluids tested, including saliva, gave positive reactions although a slight positive reaction with faecal material was recorded.