A guide to interpreting single locus profiles of DNA mixtures in forensic cases.

Analysis of a mixed body fluid crime sample by means of a single locus DNA probe may give rise to several bands. If a suspect is found to have a profile which matches two of the bands, then the evaluation of the evidential strength requires careful analysis. This paper describes the analysis of two relatively simple case examples. It is intended that the principles of the interpretative process will provide a guide to caseworkers who may encounter similar cases. The extension of the treatment to more complex cases should be clear.     

Experiences with single locus DNA probes in casework.

DNA profiling in this laboratory has been employed primarily in cases of sexual assault and the largest category of items examined has been internal vaginal swabs. 79% of these gave a profile which was different from that of the victim. Results have been obtained from swabs taken up to 70 h after intercourse. In cases where DNA results were obtained, one or more suspects were excluded in 29% of the cases.     

Testing for seasonality in reported crime data

In spite of the apparent importance of crime statistics to policy-makers and the public, these data are not often analyzed or refined in the same manner as other social series such as unemployment. In this paper, seasonal variation in FBI index crimes is investigated for a major urban area. Using Miami data for 1949–1970, a test for seasonality is developed and seasonal indices are constructed for a number of crime types. A definite seasonal pattern in Miami crime data is found to exist, although its importance seems to be declining in recent years. Some applications of seasonally adjusted data to public information and operations are also briefly discussed.     

An extended likelihood ratio framework for interpreting evidence.

This paper reviews some current methods, the likelihood ratio-based approach and the full Bayesian approach for the interpretation of evidence and discusses previously identified shortcomings in them. It suggests an approach based on a compromise--based on an extended likelihood ratio--that may combine the merits of logic without overstepping acceptable bounds for the forensic scientist in the presentation of evidence. The approach is exposed formally and takes advantage of inferential networks called Bayesian networks.     

A more efficient extraction method of human bone resulting in improved DNA profiling

Eight human bone samples, from a forensic case, were extracted in parallel using our standard protocol with and without PTB in the buffer. Both methods were sometimes inadequate for (complete) STR profiling, while the presence of PTB even decreases the DNA yield.The complete decalcification of the bone extraction residues in an EDTA-solution with SDS recovered sufficient amounts of DNA, which resulted in complete STR profiling for all samples. Complete decalcification without SDS yielded even higher amounts of DNA and also complete STR profiling for all samples.Similar results were obtained for the DNA extraction from a human tooth.     

A continuous model for interpreting the positions of bands in DNA locus-specific work.

A simple but rigorous approach is offered for evaluating the evidential value of single locus DNA autoradiographs. This approach does not use a binning technique and it does not treat alleles as discrete variables. Instead, the allele distribution is considered to be continuous. The variation between two comparable bands is assessed using previously determined experimental parameters. The Bayesian treatment leads to an expression of the "quality of a match".     

The use of acid phosphatase test papers for DNA profiling.

The acid phosphatase (AP) test is a routine assay used to screen casework items for the possible presence of semen. This colour test is carried out on filter paper which is retained after testing. Two-year-old AP test papers were found to contain sufficient DNA for short tandem repeat (STR) profiling. Prior to polymerase chain reaction (PCR) amplification, the DNA was preferentially separated into sperm depleted and sperm enriched cell fractions. The implication of these findings for past and present cases is discussed.     

Carrying weapons to school for protection: An analysis of the 2001 school crime supplement data

This study focused on the reasons why adolescents bring guns to schools. It is argued that the etiology for carrying other weapons to school is not the same as that for carrying a gun to school for protection. Data from a nationally representative sample of school youth were analyzed with an appropriate analytic technique—multinomial logistic regression in dealing with nominal dependent variable. The results supported the hypotheses that both correlates and correlational strengths of carrying guns and other weapons to school for protection are different. Such factors as others' drug use, gangs at school, skipping school, perception, and age influence the probability of carrying other weapons to school, but are not related to carrying a gun to school. The three factors that relate to both carrying a gun and other weapons to schools are physical fights, peers' carrying guns, and gender. Their correlational strengths, however, are quite different.     

Investigation of the between-gel and within-gel variation in fragment size determinations found when using single locus DNA probes.

Measurement variation in the sizing of DNA fragments has been assessed, examining within-gel and between-gel variability. Also, measurement variation detected between two different laboratories, using both manual and automated measurement techniques, has been investigated and discussed.     

Cocaine profiling for strategic intelligence, a cross-border project between France and Switzerland: part II. Validation of the statistical methodology for the profiling of cocaine

Harmonisation and optimization of analytical and statistical methodologies were carried out between two forensic laboratories (Lausanne, Switzerland and Lyon, France) in order to provide drug intelligence for cross-border cocaine seizures. Part I dealt with the optimization of the analytical method and its robustness. This second part investigates statistical methodologies that will provide reliable comparison of cocaine seizures analysed on two different gas chromatographs interfaced with a flame ionisation detectors (GC-FIDs) in two distinct laboratories. Sixty-six statistical combinations (ten data pre-treatments followed by six different distance measurements and correlation coefficients) were applied. One pre-treatment (N+S: area of each peak is divided by its standard deviation calculated from the whole data set) followed by the Cosine or Pearson correlation coefficients were found to be the best statistical compromise for optimal discrimination of linked and non-linked samples. The centralisation of the analyses in one single laboratory is not a required condition anymore to compare samples seized in different countries. This allows collaboration, but also, jurisdictional control over data.     

Murder in south London: a novel use of DNA profiling.

Lorraine Benson's body was found beaten and strangled at Raynes Park, Surrey, in December 1988. Considering the possibility of linked offences, a murder squad was set up to work alongside a team already investigating a rape series in the Kingston area. A man's handkerchief left at a site a quarter of a mile from the murder scene was found to be stained with blood and saliva matching that of the victim. A DNA profile was obtained from a stain of nasal mucus on this handkerchief and found to match a suspect later arrested for an attempted rape in the same locality. Also of forensic interest were dust marks made by the zips of the victim's and defendant's coats and identification of the rope used for strangulation.     

A comparative analysis of media reports of U.S. parricide cases with officially reported national crime data and the psychiatric and psychological literature

This article is a content analysis of 150 unique cases of children killing parents in the United States as reported in the electronic news media. The accuracy of online coverage of U.S. parricide incidents is assessed using two types of resources: officially reported national statistics on known parricidal incidents and the psychological and psychiatric literature on matricide and patricide. Comparisons of news accounts of media-reported U.S. parricide cases with Supplementary Homicide Report data indicate that electronic media coverage of parricide cases focused on the more sensational and unusual parricides. Analyses of these media accounts by offender age found 13 significant differences between juvenile and adult offenders. Ten of these 13 differences related to motive and Heide's parricide offender types (severely abused, severely mentally ill, and dangerously antisocial) and were consistent with the mental health-related literature in this area. The limitations and directions for future research are discussed at length.     

An analysis of single and multi-copy methods for DNA quantitation by real-time polymerase chain reaction

The goal of this paper was to examine and compare two different commercially available approaches to the determination of the relative quantities of autosomal and Y chromosomal DNA using real-time PCR. One, Quantifiler^® Duo, utilizes a TaqMan^® assay with single copy probes for both autosomal human and Y quantification. The other method, Plexor HY^® utilizes a primer quenching assay with multi-copy probes for its quantification of autosomal human and Y chromosomal DNA. To test these approaches we have utilized the NIST Human DNA Quantitation Standard Reference Material 2372, a set of three different NIST human DNA quantification standards, to examine the precision, accuracy and sensitivity of the real-time PCR assays. We also examined data from both systems utilizing casework samples. The results show that both systems produced linear estimates for DNA quantity over a broad range of input DNA. However we did observe some apparent copy number effects when comparing the three different NIST standards which we attributed to issues with sequence variations in the different standards. Overall, the single copy approach provided better accuracy while the multi-copy approach produced better sensitivity. Thus the choice of which system to use should depend upon the goals of the user.     

小鼠皮肤损伤后时序芯片数据分析及关键基因的筛选

目的 应用生物信息学方法对皮肤损伤后不同时间点的差异表达基因(differentially expressed genes,DEGs)进行分析,为法医学皮肤损伤时间推断(wound age estimation)提供理论依据.方法 从基因表达综合数据库(gene expression omnibus,GEO)下载基因芯...     

Development of a harmonized method for the profiling of amphetamines. I. Synthesis of standards and compilation of analytical data

Reference material was synthesised for 21 substances that are frequently present as synthetic impurities, i.e. by-products, in illicitly produced amphetamine. Each of these substances is a typical by-product for at least one of the three approaches most often used to synthesise amphetamine, namely, the Leuckart, the reductive amination of benzyl methyl ketone, and the nitrostyrene routes. A large body of data on the substances was recorded, including the following: mass spectra, ultraviolet spectra, Fourier transform infrared spectra, infrared spectra in gas phase, and 1H NMR and 13C NMR spectra.     

DNA typing for identification of some species of Calliphoridae. An interest in forensic entomology.

To determine precisely post mortem interval, larvae and puparium species found on a corpse have to be identified. Among more than 200 cases examined at the entomology department of the Institut de Recherche Criminelle de la Gendarmerie Nationale, two-thirds concerned corpses less than one month old. Therefore, insects from first and second screwworms are the most frequently found [1]. Some species commonly found in France, such as different Lucilia and Calliphora vicina Robineau-Desvoidy, are easily identifiable at an adult stage, but are almost impossible to differentiate at immature stages when only fragments of puparium or necrosed first instar larvae are available. For this reason, an easy and objective method of identification was thus searched by genetic analysis of these insects. Sequencing of partial gene of sub unit I of cytochrome oxydase has been used to predict restriction sites. Restriction enzyme cleavage of PCR products with Dde I allowed us to differentiate these species.     

On organized crime and police cooperation in the European union - Lessons learned. An interview with Professor Cyrille Fijnaut.

Professor Fijnaut sheds new light on understanding organized crime from a multifaceted perspective. Organized crime in Europe, as in America, confronts law enforcement agencies with new challenges which demands new and different perspectives in order to effectively fight current and future threats. By focusing on the violence associated with organized criminals and on formal mechanisms involving control and trust as basis for inter-agency linkages, he circumscribes two of the most challenging issues in dealing with organized crime. He points out that organized crime groups are not necessarily hierarchical, stable and functional in the way they conduct their business. Professor Fijnaut makes the point that the impact of organized crime groups' activities extend well beyond the strictly criminal arena.