Applicability of the ParaDNA® Screening System to Seminal Samples

Seminal fluid represents a common biological material recovered from sexual assault crime scenes. Such samples can be prescreened using different techniques to determine cell type and relative amount before submitting for full STR profiling. The ParaDNA^® Screening System is a novel forensic test which identifies the presence of DNA through amplification and detection of two common STR loci (D16S539 and TH01) and the Amelogenin marker. The detection of the Y allele in samples could provide a useful tool in the triage and submission of sexual assault samples by enforcement authorities. Male template material was detected on a range of common sexual assault evidence items including cotton pillow cases, condoms, swab heads and glass surfaces and shows a detection limit of 1 in 1000 dilution of neat semen. These data indicate this technology has the potential to be a useful tool for the detection of male donor DNA in sexual assault casework.     

Trace DNA: a review,discussion of theory,and application of the transfer of trace quantities of DNA through skin contact

Advances in STR PCR DNA profiling technology allow for the analysis of minute quantities of DNA. It is frequently possible to obtain successful DNA results from cellular material transferred from the skin of an individual who has simply touched an object. Handling objects, such as weapons or other items associated with a crime, touching surfaces, or wearing clothing, may represent sufficient contact to transfer small numbers of DNA bearing cells, or trace DNA, which can be successfully analyzed. With this minimal amount of contact required to yield a suspect profile comes tremendous crime solving potential, and a number of considerations for prudent application, and the maximization of evidentiary value. Evidentiary materials not previously considered must be recognized and preserved, and the resulting DNA type profiles interpreted in their proper forensic context.     

The effects of deprivation on the time spent examining crime scenes and the recovery of DNA and fingerprints

DNA and fingerprint identifications are now accepted as an integral part of the investigation of a wide range of criminal offences from burglary and auto crime to serious and major crime. Despite this, there is still much variation between U.K. police forces in the recovery of fingerprint and DNA material from crime scenes. Analysis of burglary and auto crime data for Northamptonshire, U.K., during a 3-year period has enabled an examination of the relationship between the deprivation of the neighborhood in which the crime was committed and the level of service provided by Crime Scene Examiners. The results indicate that the time spent examining a crime scene for forensic evidence is not affected by the deprivation of the neighborhood. Further, there is no statistical significance between deprivation and the recovery of fingerprints from the crime scene. The relationship between deprivation and DNA recovery is, however, statistically significant with DNA being recovered more frequently from less deprived neighborhoods.     

Application of plant DNA markers in forensic botany: genetic comparison of Quercus evidence leaves to crime scene trees using microsatellites

As highly polymorphic DNA markers become increasingly available for a wide range of plant and animal species, there will be increasing opportunities for applications to forensic investigations. To date, however, relatively few studies have reported using DNA profiles of non-human species to place suspects at or near crime scenes. Here we describe an investigation of a double homicide of a female and her near-term fetus. Leaf material taken from a suspect's vehicle was identified to be that of sand live oak, Quercus geminata, the same tree species that occurred near a shallow grave where the victims were found. Quercus-specific DNA microsatellites were used to genotype both dried and fresh material from trees located near the burial site and from the material taken from the suspect's car. Samples from the local population of Q. geminata were also collected and genotyped in order to demonstrate that genetic variation at four microsatellite loci was sufficient to assign leaves to an individual tree with high statistical certainty. The cumulative average probability of identity for these four loci was 2.06x10(-6). DNA was successfully obtained from the dried leaf material although PCR amplification was more difficult than amplification of DNA from fresh leaves. The DNA profiles of the dried leaves from the suspect's car did not match those of the trees near the crime scene. Although this investigation did not provide evidence that could be used against the suspect, it does demonstrate the potential for plant microsatellite markers providing physical evidence that links plant materials to live plants at or near crime scenes.     

Forensic comparison of soils by bacterial community DNA profiling

This preliminary investigation has shown that a soil microbial community DNA profile can be obtained from the small sample of soil recovered from the sole of a shoe, and from soil stains on clothing. We have also shown that these profiles are representative of the site of collection and therefore could potentially be used as associative evidence to prove a link between suspects and crime scenes. Soil community profiles were obtained using the T-RFLP fingerprinting method that uses fluorescent primer technology and semi-automated analysis techniques similar to those used in human DNA profiling in forensic laboratories.     

Recovery of trace DNA and its application to DNA profiling of shoe insoles

In recent years, the analysis of trace amounts of DNA has become a necessary and useful forensic tool. DNA profiles can be obtained from items that have been worn or handled, due to the presence of transferred DNA derived from skin cells. Shoeprints collected from crime scenes that match a suspects shoe can link a shoe to the crime scene. A DNA profile from inside the shoe can link a wearer to a shoe thus increasing the evidential value of the forensic evidence. In this work, variation in the amount of DNA recovered from hands and feet of different individuals is investigated. Sites for sampling DNA from shoe insoles are compared and a protocol for the subsequent sampling and extraction is developed. Finally, a case study is described where DNA analysis of shoe insoles has provided forensic evidence.     

Swabs as DNA Collection Devices for Sampling Different Biological Materials from Different Substrates

Currently, there is a variety of swabs for collection of biological evidence from crime scenes, but their comparative efficiency is unknown. Here, we report the results of an investigation into the efficiency of different swab types to collect blood, saliva and touch DNA from a range of substrates. The efficiency of extracting blood and saliva from each swab type was also tested. Some swabs were significantly more effective than others for sampling biological materials from different substrates. Swabs with the highest sampling efficiency, however, often did not have the highest extraction efficiency. Observations were recorded regarding practicality of each swab in a variety of situations. Our study demonstrates that selection of sampling device impacts greatly upon successful collection and extraction of DNA. We present guidelines to assist in evaluation of swab choice.     

犯罪现场生物检材的发现、提取策略

在改进现场生物检材的发现和提取技术的同时,也要进行理论创新和体系构建,才能够更好地指导实践。全局的观点、具体案件具体分析和犯罪现场重建对于现场勘查中有效地发现、提取和利用生物检材是十分重要的。     

Evaluating DNA profiles in a case where the defence is "it was my brother".

The widespread application of DNA profiling has brought to some prominence the issue of close relatives sharing body fluid types. In a particular crime case it may be suggested that a close relative of the suspect was the person responsible. This paper explains how an assessment may be made in the context of single locus profiling and where the suggestion is that a full sibling is involved. A formula is established for the likelihood ratio which is then worked out in detail for the particular case where the suspect profile has two distinct bands. Generalization to other types of case is briefly explained and there is a short discussion of the impact of the evidence in the context of a trial. For all parties, justice will best be done if the scientist has ample notice, before the trial, of relationship issues such as this one.     

Performance testing of commercial containers for collection and storage of fire debris evidence

Fire debris evidence may contain ignitable liquid residues valuable in the investigation of a potential arson scene. The ability to obtain evidence containers that are contaminant-free and vapor-tight is essential to the analysis and storage of fire debris evidence. Commercial containers such as metal "paint" cans, glass mason jars, and polymer bags are often employed as fire debris evidence containers. The purpose of this research was to determine which of these three types of containers provided the most vapor-tight seal for the prevention of ignitable liquid vapor loss and to assess the potential for cross-contamination. Leak rates for each type of container were measured under controlled conditions. Simple mixtures of hydrocarbons were utilized in these experiments. Leak rates were determined based on the amounts of hydrocarbon recovered from activated charcoal located outside the test container and within a secondary container. Quantitation of the hydrocarbons recovered from activated charcoal was calculated using external standard calibration curves following analysis by gas chromatography-mass spectrometry. The results demonstrated that glass jars had the fastest leak rate followed by metal paint cans and properly heat-sealed polymer bags with the slowest leak rate. Each container exhibited a different leak mechanism, which resulted in an observable effect on the composition of hydrocarbons lost from the container. Hydrocarbon transfer from one container to another is also demonstrated. This study presents results that reveal the most vapor-tight container to be a properly heat-sealed copolymer bag.     

Investigation into the usefulness of DNA profiling of earprints

DNA profiling of biological trace evidence has been used for many years. The application of this technique specifically to the DNA profiling of earprints has not to date been thoroughly investigated. This report presents the results of 60 earprints collected from three healthy adult volunteers under controlled laboratory conditions. DNA profile analysis revealed that high levels of non-donor alleles are observed when earprints are collected for DNA profiling. The source of these non-donor alleles is investigated and the impact that their presence within the profile may have on the use of this technique is discussed.     

An investigation of two methods of DNA recovery from fired and unfired 9 mm ammunition

Cartridge cases are often recovered from crime scenes involving firearms and, in the United Kingdom (where gun possession is strictly controlled), these are commonly from 9 mm calibre ammunition. The ability to obtain informative DNA profiles from touch DNA on recovered cartridges could have a significant impact on the investigation of that type of offence. However, this avenue may not be routinely considered as investigators in the UK have historically had a low expectation of obtaining useful DNA profiles. This stance may not be unreasonable given that (a) only trace amounts of DNA are likely to have been transferred onto the cartridge cases through handling; and (b) when the cartridge is spent, the potential deterioration of that DNA caused by the act of discharging the weapon.We introduce a novel semi-automatable method using direct lysis for the recovery of DNA from ammunition and compare it with a traditional double-swabbing method (using wet and dry swabs). DNA profiling of the DNA recovered using both methods was carried out using the ESI17 FAST STR system (Promega). This demonstrated a significant increase in DNA recovery using the direct lysis approach, and correspondingly improved STR results.We also investigated the effect on the recovery and profiling of DNA from fired, and unfired, 9 mm cartridges using the direct lysis technique. These results demonstrate that DNA suitable for STR analysis can still be recovered from fired ammunition with only slightly reduced yields compared to unfired ammunition. In these experiments, the handler of the ammunition was most commonly either the sole contributor or the major contributor to the recovered DNA profile.     

Assessing DNA recovery and profile determination from bloody snow

Successful DNA typing of forensically relevant evidence is reliant on both the quality and quantity of biological material recovered from a crime scene. In geographical areas of the world exposed to cold climates, it is not uncommon for biological evidence to encounter a diversity of challenging surfaces and environments, including snowy surfaces. Currently, there is no standard protocol for recovery of bloodstain evidence in snow and very few publications exploring adequate methods of recovering biological evidence from snowy surfaces. In this study, three common substrates (e.g., cotton swabs, FTA paper, and untreated filter paper) utilized by investigators for evidence recovery were evaluated for their ability to recover human blood (DNA) evidence from snow that would be viable for traditional forensic DNA typing. Each biological sample was extracted and quantified to evaluate the quality and quantity of DNA recovered. All samples yielded sufficient non-degraded DNA to proceed with DNA profiling, where complete DNA profiles were generated from each collection substrate. The experimental findings presented herein demonstrate that the ability to recover viable DNA from human blood collected on surface snow is possible using all three collection methods tested.     

SNP genotyping of forensic casework samples using the 52 SNPforID markers

The analysis of degraded DNA is one of the biggest challenges in forensic casework. SNPs, which can be amplified using small amplicons, have previously been successfully applied to the profiling of forensic evidence that could not be analyzed using conventional STRs. Here we selected the 52 SNPforID SNP markers, with amplicons that ranged in size from 59 bp to 115 bp, and used them to profile a range of casework samples from Malaysia. DNA degradation is a common problem in Malaysia due to the high temperatures and humidity. To carry out the study we modified the 52 SNPforID markers into four 13-plex SNaPshot assays to enable easier interpretation of profiles on the ABI PRISM^® 310 and 3500.Fifty-one crime samples comprising bloodstains on cloth, swabs, and a mat and 2 swabs of trace DNA from 10 crime scenes in Malaysia were profiled after DNA extraction using a phenol–chloroform method. The samples were also subjected to STR analysis using the Powerplex^® 16 system (Promega), which resulted in only 17 full profiles and 9 partial profiles; using SNPs, 36 full profiles and 5 partial profiles could be generated.     

犯罪剖绘：科学还是艺术？

犯罪剖绘（criminal profiling）为分析（连续）犯罪行为型态的技术,藉由统计技术分析潜在犯罪者、被害者与犯罪现场迹证等三者之间相互联结可能性。然犯罪剖绘技术应用至＂案件连结分析＂,可根据犯罪现场所遗留迹证（含心理迹证）,预测/推论犯罪者之人口背景特征,并将这些案件之犯罪现场迹证系统化处理,建构成数据库,有助警察侦办连续型犯罪。经由案件连结分析所得证据,能否成为法庭上论罪之依据,在英美国家必须通过＂Frye法则＂与＂Daubert测试法则＂检验,即是否已经通过科学性检验,或同一学术领域同侪认可验证过程。因此,后续研究可朝更精确统计分析方法迈进,以提升案件连结分析数据库对于预测未发现犯罪者之准确率及其法庭证据力。     

Comparison of four DNA extraction methods to extract DNA from cigarette butts collected in Lebanon

Cigarette butts collected from crime scenes represent valuable sources of DNA. However the extraction of the genetic material may deem challenging especially when different contaminants may compromise the integrity, quality, and quantity of DNA obtained. This study aims at comparing four extraction methods (Chelex-100, soaking + Chelex-100, Chelex-100?+?PK, and DNA IQ? System) with the intention of identifying the one with maximal recovery rate and profiling success. DNA was extracted using aforementioned four methods from 70 cigarette butts collected from sites across Lebanon. DNA was quantified by qPCR using TaqMan Quantifiler Kit on an Applied Biosystems 7300 SDS instrument and genotypes were obtained using the PowerPlex® 21 kit on an Applied Biosystems 3130 Genetic Analyser. The findings of this work showed that DNA extraction with Chelex-100?+?PK is preferred to the other three methods when seeking both, a high yield and the generation of maximal numbers of full profiles. The Chelex-100?+?PK method is simple, cost effective, and therefore suitable for routine cigarette butts case studies.     

DNA transfer during social interactions

Multiple DNA transfer has increasingly been brought up in court as potential means for the presence of the defendants DNA at the crime scene or on a piece of evidence. This has prompted several investigations into DNA transfer under very controlled and semi-controlled conditions, however little is published about DNA transfer in “uncontrolled” or real life situations.Here we examined the effects of multiple direct and indirect transfer of DNA within a small group of people and objects: three individuals participating in a social interaction of having a drink (jug of juice) together for 20 min. At the end of the tests all the surfaces of interest were sampled and analyzed.In many instances the last person or the only person to come in contact with the object was the main or the only depositor of the DNA detected on it. The jug was a clear vector for secondary DNA transfer. Interestingly, in many instances the participants acted as vectors for foreign DNA transfer.     

Genetic identification of biological samples buried in clay soil during summer and winter seasons

The analysis of a biological samples found in crime scenes can be a challenging task. Minute amount of DNA, degraded DNA and the presence of inhibitors in biological samples, can interfere with the achievement of a complete genetic profile.Chelating resin, silica membranes and silica-coated with paramagnetic resin were the techniques used in this study for the isolation and purification of DNA. Our aim was to find out the best DNA extraction method for application in the presence of biological samples buried in clay soil.