Comparison of the variables affecting the recovery of DNA from common drinking containers

As the boundaries of forensic DNA profiling continue to expand, less obvious sources of biological evidence are being collected at crime scenes for DNA profiling. One example is the recovery of biological evidence from common drink containers, such as bottles and cans, which have been found at crime scenes. There are many variables that may have an impact on recovering a DNA profile from such exhibits. In this research, the effects of person to person variation, time, type of drink (including alcoholic and non-alcoholic beverages), and type of drink container, were assessed for their impact on the major analytical outcomes of the DNA process. The results show that the alpha-amylase activity varies from individual to individual and is reduced in the presence of some alcoholic drinks. A reasonable DNA yield was obtained from all samples, however, the concentrations exhibited significant person to person variation. The type of drink container influenced the DNA yield with cans giving a higher yield than bottles of the same drink type. To a reduced extent the presence or absence of alcohol affected the overall DNA yield and when partial or failed DNA profiles were produced they were more likely to be associated with alcoholic drinks than non-alcoholic drinks.     

The New Zealand DNA databank: its development and significance as a crime solving tool.

The New Zealand DNA Databank was established following the introduction of legislation in August 1996. Using the Second Generation Multiplex (SGM), DNA profiles from over 13,000 convicted offenders and volunteer donors have been completed to the National DNA Database. Since June 1998, DNA profiles from over 1,400 unsolved crimes have been entered onto the Crime Sample Database. Of all unsolved crimes analysed, 33% are linked to individuals and 21% are linked to other unsolved crimes. Several high profile types of case including homicides, sexual offenses and burglaries are amongst those regularly solved.     

Sequence variation in humans and other primates at six short tandem repeat loci used in forensic identity testing

A large number of alleles from the six different short tandem repeat (STR) loci FGA, D3S1358, vWA, CSF1PO, TPOX and TH01, used in human identity testing were sequenced to provide support for the robustness of fluorescent STR DNA typing by allele size. Sequence information for some of these loci (FGA, vWA, TH01) is an extension of published work, whereas no extensive sequence information is available with respect to the D3S1358, CSF1PO, and TPOX loci. Sequencing of alleles at each locus has provided quantitative data with respect to the true nucleotide length of common alleles, and of alleles that vary in length from the common alleles. All alleles that were identified as "off-ladder" alleles through fluorescent typing at these STR loci have proven to be true length variant alleles. Sequencing at the D3S1358 and CSF1PO loci allowed for the establishment of a common nomenclature for these loci. A correlation between percent stutter and the length of the core tandem repeat is demonstrated at the FGA locus. Alleles in which the core tandem repeat is interrupted by a repeat unit of different sequence have a reduced percent stutter. DNA samples from three non-human primates (chimpanzee, orangutan, and gorilla) were compared to the human sequences, and shown to differ markedly across loci with respect to their homology. The effects of primer binding site mutations on the amplification efficiency at a particular locus, and methods used to interpret amplification imbalance of heterozygous alleles at a locus is also addressed.     

Books received

The Politics of Local Expenditure, K. Newton and T.J. Karran, Macmillan, 1985, pp. 165, £5.95 paperback.

Welfare Bureaucracies, David Billis, Heinemann, 1984, pp. 252, £11.50 paperback.

Paying for Welfare, Howard Glennerster, Black well, 1985, pp. xi + 273, £7.50.

School Governing Bodies, M. Kogan, D. Johnson, T. Packwood and T. Whitaker, Heinemann Educational Books, 1984, pp. 210, £18.50 hardback, £8.50 paperback.

Something in the Air, Andrew Blowers, Harper and Row, 1984, pp. 359, £6.95.

Controlling the Constable: Police Accountability in England and Wales, Tony Jefferson and Roger Grimshaw, Frederick Muller/The Cobden Trust, 1984, pp. 205, £18.95 hardback, £7.95 paperback.     

Industrial relations and manpower

This article provides the first empirical evidence on the impact of Best Value processes on local service quality, costs, efficiency and accountability. Views were obtained from a wide range of personnel involved in the pilot programme in Wales by means of a postal questionnaire and interviews. The evidence shows that so far Best Value has had a positive impact on quality and accountability but little impact on service costs. Perceptions of the impact of Best Value are significantly more positive in authorities that adopted a corporate approach to the pilot process.     

Evaluating interviews which search for the truth with suspects: but are investigators’ self-assessments of their own skills truthful ones?

Self-evaluation of one’s own performance has been found in prior research to be an enabler of professional development. The task of evaluation is also a core component of a model of the investigative interviewing of victims, witnesses and suspects, being increasingly used throughout the world. However, it remains the case that there has been little research as to how practitioners approach the task itself. The present study examined the topic through the lens of observing how effectively 30 real-life investigators in the UK undertook evaluation of their interviews, representing almost the entire investigative frontline workforce of a small law enforcement agency in this country. Using an established scale of measurement, both investigators’ and an expert’s ratings of the same sample of interviews were compared across a range of tasks and behaviours. It was found that in almost all the assessed behaviours, requiring of the investigators to provide a self-rating, their scores tended to significantly outstrip those applied to the sample by the expert. Reasons are explored for the investigators’ overstated assessments. Implications for practice are then discussed.     

Developing a scale to measure the presence of possible prejudicial stereotyping in police interviews with suspects: The Minhas Investigative Interviewing Prejudicial Stereotyping Scale (MIIPSS)

If police interviewers’ hold negative feelings towards certain groups, this may affect how they interview them (either as victims, witnesses or suspects) in that they may not obtain reliable accounts, being the aim of such interviews. The Minhas Investigative Interviewing Prejudicial Stereotyping Scale (MIIPSS) has been developed to assess the level of any investigative interviewers’ prejudicial stereotyping towards suspects. The current exploratory study involved semi-structured interviews with twenty people, who had previously been interviewed as suspects in England and also eight very experienced lawyers. Both their views were measured using the MIIPSS before being subjected to a Guttman analysis. Statistical analyses showed that MIIPSS satisfies the criteria for classification as a valid unidimensional and cumulative scale. Therefore, researchers could use MIIPSS as a tool to measure prejudicial stereotyping in investigative interviews. Interviewers could also use MIIPSS to monitor their own attitudes towards certain groups or individuals suspected of different types of crimes.     

Gamma Irradiation as a Biological Decontaminant and Its Effect on Common Fingermark Detection Techniques and DNA Profiling

Abstract:  The use of disease-causing organisms and their toxins against the civilian population has defined bioterrorism and opened forensic science up to the challenges of processing contaminated evidence. This study sought to determine the use of gamma irradiation as an effective biological decontaminant and its effect on the recovery of latent fingermarks from both porous and nonporous items. Test items were contaminated with viable spores marked with latent prints and then decontaminated using a cobalt 60 gamma irradiator. Fingermark detection was the focus with standard methods including 1,2-indanedione, ninhydrin, diazafluoren-9-one, and physical developer used during this study. DNA recovery using 20% Chelex extraction and quantitative real-time polymerase chain reaction was also explored. Gamma irradiation proved effective as a bacterial decontaminant with D -values ranging from 458 to 500 Gy for nonporous items and 797–808 Gy for porous ones. The results demonstrated the successful recovery of latent marks and DNA establishing gamma irradiation as a viable decontamination option.