Trace DNA Sampling Success from Evidence Items Commonly Encountered in Forensic Casework

Trace DNA analysis is a significant part of a forensic laboratory's workload. Knowing optimal sampling strategies and item success rates for particular item types can assist in evidence selection and examination processes and shorten turnaround times. In this study, forensic short tandem repeat (STR) casework results were reviewed to determine how often STR profiles suitable for comparison were obtained from “handler” and “wearer” areas of 764 items commonly submitted for examination. One hundred and fifty‐five (155) items obtained from volunteers were also sampled. Items were analyzed for best sampling location and strategy. For casework items, headwear and gloves provided the highest success rates. Experimentally, eyeglasses and earphones, T‐shirts, fabric gloves and watches provided the highest success rates. Eyeglasses and latex gloves provided optimal results if the entire surfaces were swabbed. In general, at least 10%, and up to 88% of all trace DNA analyses resulted in suitable STR profiles for comparison.     

Detection of cellular material within handprints

A novel technique for the visualisation of cellular material has been published harnessing an external binding nucleic acid fluorescence dye, Diamond™ dye (DD), in combination with a digital fluorescence microscope. This technique can effectively detect cellular material on an object transferred by touch allowing targeted collection of latent DNA. Previous studies on the visualisation of touch DNA have focussed on transfer from fingertips only.Here we report on the visualisation of cellular material transferred via twenty different positions over the entire handprint. Three volunteers (a heavy, an intermediate and a light shedder) were asked to press their hands onto a plastic surface with medium pressure for 15 s at undefined time points post-handwashing, creating a complete handprint. DD was applied to the entire area and the presence of cellular material was recorded based on cells within 5 separate frames at each of the 20 positions. All tests were performed in triplicate such that the final dataset contained 1,800 observed frames.This extensive study allows accurate monitoring of cellular transfer deposited by different parts of the hand. Our study highlights which areas of an individual’s hand shed the greatest, or least, amount of cellular material. This simple process can act as a guide for DNA collection from items held within the entire hand, rather than only touched by the fingertips only, such as weapons, knives and steering wheels.     

Shedder status—An analysis over time and assessment of various contributing factors

The shedder status of a person is an important consideration when evaluating probabilities of DNA transfer during activity-level assessments. As an extension of our previously published study, the shedder statuses of 38 individuals were reassessed 1 year later. The study found that shedder status may change over time for some individuals and was associated with one's gender, number of items touched, and mobile phone usage. In 29% of touch events, no DNA allele was detected and in 99% of touch events, the amount of DNA deposited was <2 ng. The study also found that in 0.6% of touch events, the participant could be excluded as a contributor of the observed DNA profile, with another person being included. Additionally, our investigations suggest that the current three-category system for shedder status classification may require further refinement to better represent the individuals' shedder status in a population.     

The tendency of individuals to transfer DNA to handled items

This research investigates factors influencing the transfer of DNA to handled objects and the process known as 'shedding'. Volunteers were recruited to hold sterile plastic tubes using experiments originally designed by Lowe et al. [A. Lowe, C. Murray, J. Whitaker, G. Tully, P. Gill, The propensity of individuals to deposit DNA and secondary transfer of low level DNA from individuals to inert surfaces, Forensic Sci. Int. 129 (2002) 25-34]. Transferred cellular material was collected from the tubes and STR profiles generated using the AmpFlSTR SGM Plus multiplex with 28 and 34 PCR cycles. Volunteers were asked to hold the tubes with each hand, and to participate in a series of handwashing experiments. The DNA profiling results obtained from the transferred skin cells were compared. An attempt was made to characterize the volunteers as 'good' or 'bad' shedders and to establish which, if any, of the experimental variables were associated with 'good' shedding. Our results suggest that many factors significantly influence shedding, including which hand an individual touches an item with and the time that has elapsed since they last washed their hands. We have found that it may be more complicated than previously reported to categorise a person as being either a 'good' or a 'bad' shedder and that if truly 'good' shedders exist they may be significantly rarer than some have estimated. In the current research no 'good' shedders were observed in a group of 60 volunteers. Given these results, it seems that rather than being applied to individual forensic cases, knowledge of shedding characteristics will be most useful in providing general background data for the interpretation of trace DNA evidence.     

Evaluating the Efficiency of Primer Extension Capture as a Method to Enrich DNA Extractions,

In this study, we sought to document the efficiency of primer extension capture (PEC) as a method to enrich DNA eluates of targeted DNA molecules and remove nontarget molecules from pools containing both. Efficiency of the method was estimated by comparing number of “copies in” to “copies out” by quantitative polymerase chain reaction. PEC retention of DNA targets ranging 109‐288 base pairs (bps) in length was 15.88–2.14% (i.e., loss of 84.12–97.86% of target molecules). Experimental modifications of the PEC method resulted in no significant improvements. However, the benefit of PEC was revealed in its ability to remove most nontarget DNA molecules (99.99%). We also discovered that many (56.69%) of the target molecules are “lost” prior to their immobilization on the streptavidin‐coated beads. These estimates of methodological efficiency are directly comparable to previous ones observed following “fishing” for DNA, an alternative method for DNA enrichment.     

The propensity of individuals to deposit DNA and secondary transfer of low level DNA from individuals to inert surfaces

We have shown that there is a difference between individuals in their tendency to deposit DNA on an item when it is touched. While a good DNA shedder may leave behind a full DNA profile immediately after hand washing, poor DNA shedders may only do so when their hands have not been washed for a period of 6h. We have also demonstrated that transfer of DNA from one individual (A) to another (B) and subsequently to an object is possible under specific laboratory conditions using the AMPFISTR SGM Plus multiplex at both 28 and 34 PCR cycles. This is a form of secondary transfer. If a 30 min or 1h delay was introduced before contact of individual B with the object then at 34 cycles a mixture of profiles from both individuals was recovered. We have also determined that the quantity and quality of DNA profiles recovered is dependent upon the particular individuals involved in the transfer process. The findings reported here are preliminary and further investigations are underway in order to further add to understanding of the issues of DNA transfer and persistence.     

Co-constituting narrative: the role of researcher identity bids in qualitative interviews with women ex-offenders

Narrative criminology draws upon the stories of the research participants to better understand crime. These narratives are shaped not only by a range of structural, institutional and individual factors, but by dynamics within the interview itself. As both participant and interviewer deploy narrative techniques, they co-constitute identity meanings during the interview process. This study examines interviews with 30 women recently released from incarceration to identify ways that the researcher constructed and “bid” for identity meanings through narrative during the interview process. Specifically analyzed are the researcher’s “small stories” put forth in response to participants during the interview exchange. Ultimately, the co-constitutive nature of interview dynamics suggest that the researcher’s identity bids via small stories have implications for how participants assert their own identity meanings, account for their experiences, and ultimately orient or conceptualize their futures.     

Addressing the alternate hypothesis: Transfer and persistence of saliva beneath fingernails

This study investigated the transfer and persistence of salivary DNA under fingernails. This was performed to address a common alternate hypothesis presented to scientists in court, asserting that a relatively large quantity of DNA detected beneath the fingernails, typically from a victim of crime, originates from innocuous transfer of saliva in a casual setting.It was determined through these studies that contact with liquid saliva was an effective way to transfer foreign DNA beneath fingernails. However, when saliva was dried, DNA did not readily transfer through casual contact.When liquid saliva was placed directly beneath fingernails the amount of DNA detected from the saliva donor twenty-four hours later was several hundred-fold lower than the amount detected when sampling occurred immediately following deposition. Furthermore, when the recipients’ hands were washed immediately following the deposition of liquid saliva beneath fingernails, the majority of foreign DNA was removed following one hand washing and all detectable foreign DNA was removed from most recipients’ hands after three or six hand washings.This study demonstrates that casual contact with wet saliva can result in the transfer of substantial quantities of DNA beneath fingernails but that it does not typically persist for extended periods of time and is mostly removed if the hands are washed soon after deposition.     

An innovative transfer DNA experimental design and qPCR assay: Protocol and pilot study

Forensic “touch” DNA samples are low-quantity samples that are recovered from surfaces that have been touched by single or multiple individuals. These samples can include DNA from primary contributors who directly touched the surface, as well as secondary contributors whose DNA was transferred to the surface through an intermediary. It is difficult to determine the type of transfer, or how often and under what conditions DNA transfer occurs. In this paper, we present an innovative protocol that combines (1) a paired male and female transfer DNA experimental design in which the presence of male DNA indicates secondary transfer and (2) a cost-effective quantitative PCR (qPCR) assay of a sex-specific region in the Amelogenin gene to detect male and female DNA. We evaluate the ability of the Amelogenin qPCR assay to detect low concentrations of male and female DNA in mixed samples. We also test experimental DNA samples using our transfer DNA protocol to differentiate primary and secondary DNA transfer. Male DNA was detected in the majority of known mixed samples, even in samples with 4× more female DNA—this result demonstrates the ability to detect low concentrations of male DNA and the presence of secondary transfer DNA in our experimental design. Primary DNA transfer was detected in 100% of our experimental trials and secondary DNA transfer was detected in 37.5% of trials. Our innovative protocol mimics realistic case scenarios to establish rates of primary and secondary DNA transfer in an inexpensive and simplified manner.     

The transfer of touch DNA from hands to glass, fabric and wood

The transfer of DNA from hands to objects by holding or touching has been examined in the past. The main purpose of this study was to examine the variation in the amount of DNA transferred from hands to glass, fabric and wood. The study involved 300 volunteers (100 for glass, 100 for fabric and 100 for wood) 50% of which were male and 50% female. The volunteers held the material for 60 s. The DNA was recovered from the objects using a minitape lift, quantified using the Quantifiler kit assay, extracted using a ‘Qiagen^® QIAamp DNA mini kit’ and amplified using the AmpFlSTR^® SGM Plus™ Amplification Kit at 28 cycles. The results show that using ANOVA there was a significant difference (F = 8.2, p < 0.05) between the three object types in the amount of DNA recovered. In terms of DNA transfer and recovery, wood gave the best yield, followed by fabric and then glass. The likelihood of success of obtaining a profile indicative of the holder was approximately 9% for glass samples, 23% for fabric and 36% for wood. There was no significant difference between the amount of DNA transferred by male or female volunteers. In this study good shedder status, as defined by obtaining useful profiles of 6 or more alleles, is estimated at approximately 22% of the population. The phenomenon of secondary transfer was observed when mixed DNA profiles were obtained but the incidence was low at approximately 10% of the total number of samples. DNA profiles corresponding to more than one person were found on objects which had been touched by only one volunteer. Although secondary transfer is possible the profiles obtained from touched objects are more likely to be as a result of primary transfer rather than a secondary source.     

A study of DNA transfers onto plastic packets placed in personal bags

The ability to detect low level DNA brings with it the uncertainty of whether the detected DNA is a result of transfer. To address this uncertainty, a simulation study was conducted in which a mock illicit drug packet was placed into the personal bags of individuals. When the average transit time of the packets was increased from around 2 h to more than 14 h, the percentage of the DNA profiles recovered from the packets which could be attributed to the individuals increased greatly from 5.3% to 48.6%. We found that drug packers who were poor shedders could not be included as contributors to the DNA profiles from the drug packets at all and there was a higher chance that individuals other than themselves could be included as contributors to the DNA profile recovered from drug packets. We also found that it was equally likely that the drug packers who had direct contact with the drug packets and bag owners who did not, could be included as contributors to the DNA profiles recovered from the packets. The results in this study highlight the importance of taking into consideration the transit time of drug packet, the shedder status of the alleged packer and the history of an item, when evaluating DNA evidence in the context of illicit drug activities.     

Advantage of ForensiX Swabs in Retrieving and Preserving Biological Fluids

This study compares two novel swabs (forensiX) with a standard cotton swab (EUROTUBE) for the collection of saliva stains on glass slide for STR analysis. ForensiX collection tubes are a standard cotton swab in an “active drying” tube, where swab sample is soon dried by its innovative tube surface of the wall. The other is forensiX Nylon Flocked Swab. The study is two phases: The first “phase” assesses swab types regarding to retrieve ability of saliva. The second “phase” compares the drying ability of each swab to assess how crime samples would fare when left in storage. The main result showed that “active drying” is effective to store swabbed sample. The forensiX swabs generally are effective for higher (twofold to fourfold) DNA yield compared to delta lab swab (around 750 pg and 250 pg from 0.5 μL of saliva), respectively. These findings demonstrate the importance of drying performance in the preservation of DNA and swab selection.     

法医DNA分析的其他应用

综述了法医DNA的多种用途,如人死后根据体内DNA变化情况推断死后时间间隔,利用线粒体DNA4977bp的缺失以及端粒的长度推断年龄;利用昆虫mtDNA的细胞色素氧化酶亚基I进行昆虫种属鉴定,以帮助确定人的腐尸死亡时间;利用一些食血昆虫体内的人DNA帮助了解与案件的关系;利用DNA标记进行动物如犬、牛、马及猪等个体识别与亲子鉴定,解决因动物引起的纠纷,或者利用DNA分析嫌疑人周围的动物毛发、植物及土壤微生物等,确定嫌疑人与案件的关系。     

The Shadow Price of Social Change and Its Evaluation

This paper analyzes the “shadow price” of social transformation. For the first time, an attempt was made to determine the approaches to measuring this value with regard to nonmarket phenomena and processes, and to apply these approaches in an empirical analysis, based on a representative survey in Russia (N = 1,000) using experimental situations.

Specifically, it quantitatively evaluates (1) the degree of divergence between the real and the ideal structure of the time budget of several important domains of social life; (2) the ratio of social ills to social benefits; (3) individual public welfare functions; and (4) the social cost, legitimated by citizens, of reproducing two fundamental public goods: “the capacity to maintain ‘superpower’ status” and “the well-being of the future generations.”

The authors introduce and operationalize the novel concept of the socially suboptimal product of labor, that is, the product resulting from alienated (or unwilling) labor, and conversely, the product that could potentially result from using unutilized willing labor. In doing so we support the idea of distinguishing productive and unproductive forms within both the notion of labor and the notion of leisure. Aggregated estimates of these values show the share of gross domestic product (GDP) that could be optimized due to a redistribution of the time budget of the population between the main areas of life, according to ideal social preferences.

The balance of social benefits and social ills resulting from the life experiences and activities of individuals is empirically evaluated. We consider this balance, which is the sum of impacts of the social environment on the individual, as a suitable model for explaining how individuals make decisions about whether or not to participate in public life.

“Individual public welfare functions” are assessed empirically, demonstrating that individual utility depends on personal and collective consumption. Empirical testing covered a wide range of nation-building areas with public investment in relevant types of merit and public goods.

Then the authors propose and test on empirical data an opportunity cost approach to evaluating socially legitimate amounts of funding for the fundamental social benefits “superpower” or “additional power” of the nation.

The cost of the public good “well-being of the future generations” is calculated for the Russian sample.

Finally, the estimates of the discount rates of human lives and “healthy and prosperous years of life” were obtained for Russia for the first time.

The findings of the study are relevant for the efficient management of complex socioeconomic systems. The authors strongly believe that revealing the structure of existing social preferences and estimating their impact on various areas of social life will help improve policymaking by explicitly taking into account the specifics of the real social contract between the state and society.     

A novel FTA™ elute card collection method that improves direct DNA amplification from bloodstained concrete

Concrete is a common construction material found in residential and commercial buildings, bridges and parking lots that is a composite matrix containing aggregate held together with cement. The porous nature of concrete can make the collection and genotyping of biological fluids, such as blood, challenging. Forensic evidence can become embedded within the matrix, potentially reducing the amount of DNA available for analysis. In forensic science, “direct” amplification refers to a genotyping method that amplifies a DNA profile directly from a sample without DNA extraction, saving time and money. We investigated a novel application of Whatman? FTA? Elute cards in their ability to directly amplify PowerPlex® Fusion and Y23 profiles from minute amounts of blood that had been deposited on different concrete structures. In comparison to traditional collection methods, directly profiling blood stained construction materials using FTA? Elute cards increased the percentage loci amplified and significantly improved both allele peak height and peak height ratio while reducing allelic drop-out. FTA? Elute cards can provide a reliable, inexpensive and superior alternative to traditional methods.     

中国刑事专家辅助人向专家证人的角色转变

中国的刑事专家辅助人具有既类似于律师又类似于鉴定人、证人的多重属性;围绕专家辅助人意见的性质,也形成了质证方式说、鉴定意见说、证人证言说等多种观点。角色定位上的混乱,不仅造成了独具特色的鉴定人与专家辅助人的双轨制,而且常常使专家辅助人意见的法庭采信陷入困境。从最高人民法院有关专家辅助人的新近规定看,专家辅助人的角色呈现出向专家证人转变的趋势。这种转变的核心要求,一是实现鉴定人和专家辅助人的诉讼地位平等,专家辅助人意见和鉴定意见在专家证言意义上的证据效力平等;二是使专家辅助人回归专家证人本色,将强加给专家辅助人的不合理的质证职责交还给律师、检察官;三是提高律师、检察官熟练运用交叉询问规则、对科学证据进行质证的能力,充分发挥法官的科学证据“守门人”作用,以适应事实认定科学化的需要。     

Single source DNA profile recovery from single cells isolated from skin and fabric from touch DNA mixtures in mock physical assaults

The ability to obtain DNA profiles from trace biological evidence is routinely demonstrated with so-called ‘touch DNA evidence’, which is generally perceived to be the result of DNA obtained from shed skin cells transferred from a donor's hands to an object or person during direct physical contact. Current methods for the recovery of trace DNA employ swabs or adhesive tape to sample an area of interest. While of practical utility, such ‘blind-swabbing’ approaches will necessarily co-sample cellular material from the different individuals whose cells are present on the item, even though the individuals' cells are principally located in topographically dispersed, but distinct, locations on the item. Thus the act of swabbing itself artifactually creates some of the DNA mixtures encountered in touch DNA samples. In some instances involving transient contact between an assailant and victim, the victim's DNA may be found in such significant excess as to preclude the detection and typing of the perpetrator's DNA. In order to circumvent the challenges with standard recovery and analysis methods for touch DNA evidence, we reported previously the development of a ‘smart analysis’ single cell recovery and DNA analysis method that results in enhanced genetic analysis of touch DNA evidence. Here we use the smart single cell analysis method to recover probative single source profiles from individual and agglomerated cells from various touched objects and clothing items belonging to known donors. We then use the same approach for the detection of single source male donor DNA in simulated physical contact/assault mixture samples (i.e. male ‘assailant’ grabbing the wrist, neck or clothing from the female ‘victim’, or being in transient contact with bedding from the ‘victim’). DNA profiles attributable to the male or female known donors were obtained from 31% and 35% of the single and agglomerated bio-particles (putative cells) tested. The known male donor ‘assailant’ DNA profile was identified in the cell sampling from every mixture type tested. The results of this work demonstrate the efficacy of an alternative strategy to recover single source perpetrator DNA profiles in physical contact/assault cases involving trace perpetrator/victim cellular admixtures.     

身份犯及其相关概念辨析

身份犯是指刑法规定的以行为人所具有的特定身份作为犯罪构成要件或量刑情节的犯罪。身份犯不同于亲手犯和不作为犯,身份犯是以犯罪主体是否具有特定身份为标准对犯罪进行分类的结果,亲手犯是根据实行行为是否可以和主体相分离而对犯罪所作的一种分类,不作为犯则是以实行行为的表现形式为标准划分的一类犯罪,三者既有区别,又有联系。     

Effects of Educational Motives on Prisoners’ Participation in Education and Educational Desires

There are numerous individual and social benefits of increasing prisoners’ educational motivation and their level of education. During incarceration they can be motivated to consider education because of the value of education, their own resettlement, future job prospects, to break free from prison routines, or simply to be around others. The aim of the present study was to examine the relationship between prisoners’ educational motives and their participation in education or desires to start an education in prison. The participants were 750 prisoners who attended prison education in Norwegian prisons in 2009, plus 898 other prisoners. Three motive categories were identified: “Future planning”, “Social reasons and escapism”, and “Competence building” (learning for the sake of learning). The first factor explained more than twice of the variance of the sum of the two others. Prisoners with high scores in the competence building category were significantly more prone to participate in education in prison, also when other commonly used background variables were controlled for statistically. Among those who did not participate, high scores in competence building also predicted that they desired to start an education while incarcerated. Prisoners with high scores in the future planning category were less likely to participate in prison education. We then discuss why this latter somewhat surprising negative effect occurred.     

From Sore Throats to Greenland: Howard Brenton’s Utopian Plays

British playwright Howard Brenton once wrote, “There is an infinite variety of ways of making theatre, but only one theme which, inevitably, Aeschylus was onto—it’s simply ‘how can we live justly?’” Brenton’s entire oeuvre reflects his struggle to answer this basic question but he has specifically characterized three of his plays as Utopian. These are Sore Throats, Bloody Poetry, and Greenland. The plays comprise a journey which begins, in the playwright’s words, “far from human dignity and peace” and ends 700 years from now with a vision of Brenton’s hopes for the future: “how I hope my children, or my children’s children’s children, will live and think.” The works explore the nature of love, individual relationships, and sexual roles as these relate to issues of power and manipulation. The corrupting power of money, and English complacency and acquiescence, are additional major themes. Finally, they all confront the question of human responsibility and its relationship to the individual and to society. Ultimately, they offer us an unmerciful look at the worst of human nature and a liberating vision of the good we are capable of achieving.