A rape case solved by mitochondrial DNA mixture analysis

In cases of stains that contain mixed DNA from different contributors, analyzing mitochondrial DNA (mtDNA) requires the use of cloning techniques. We developed an efficient cloning technique that was applied in a rape case. After a differential lysis-based DNA extraction from vaginal swabs, hypervariable region I and II (HVI, HVII) amplicons obtained from the male fraction were cloned. Although we mainly found the victim's haplotype, we were able to detect the suspect's haplotype in two clones for HVI and in one clone for HVII. As the midpiece of the flagellum, which contains mitochondria, can be lost during the differential lysis, we also investigated the female fraction by cloning to evaluate the proportion of victim/suspect mtDNA. Unfortunately, only clones presenting the victim's haplotype were found. This case highlights the need for an optimal differential lysis protocol to enrich the male fraction not only with nuclear but also mitochondrial DNA.     

Suicidal hanging resulting in complete decapitation--forensic, radiological, and anthropological studies: a case report

The authors report a case of complete posthanging decapitation. The decapitated corpse lay against a pillar of a road bridge. The head had rolled 5 m from the trunk. The bridge was 7.2 m above the road level. The rope was 3.6 m long, its lower end was 3.6 m from the ground and its diameter was 10 mm. The noose used was a slip knot. Plain X-rays of the skull and cervical spine were obtained. The skull X-rays showed air in the meningeal spaces, in both lateral and third ventricles. The severance plane of the cervical spine was between the third and the fourth cervical vertebrae. No other cervical vertebral injuries were noted. At autopsy, the brain was macroscopically unremarkable except for air in the meningeal veins. The decapitation injuries of the head and the torso corresponded perfectly, without apparent loss of substance. The severance plane was confirmed. Dry bone study was carried out. Except for fractures of the extremities of the spinous processes of the second and third cervical vertebrae, no other bone injury of the spine was seen. The cervical vertebrae displayed numerous osteoarthritic lesions. The traditional hangman's fracture was not found. To the best of our knowledge, this is the first report of complete posthanging decapitation with a severance plane between the third and fourth cervical vertebrae.     

Biological variability of the minutiae in the fingerprints of a sample of the Spanish population

The minutiae, a term coined by Galton to refer to the small peculiarities present along the length of every isolated ridge, or characteristic points, a term used primarily by the Spanish Police Scientists, have an inter- and intrapopulation variability which has not been extensively studied. However, these peculiarities constitute the bases for the fingerprint identification of individuals in the field of criminology. Using the adhesive paper and graphite method, the fingerprints of 200 students, 100 males and 100 females, with ages ranging between 20 and 35, have been taken at the University of Alcala (Madrid). From this sample, the distal phalanx of the index finger of the right hand has been studied. The total count of the minutiae, as well as that of each different type, was made of the entire print area, and inside and outside of a circle with a radius of 18 ridges. The highest frequencies were of ridge endings, followed by bifurcations and convergences, all others appearing with frequencies of lower than 5%. The distribution of the minutiae was not homogeneous for the area of the fingerprint (inside and outside the circle). In the study of minutiae statistically significant differences were found between the sexes, and between the different types of general pattern (arches, loops, and whorls).     

Resolving paternity relationships using X-chromosome STRs and Bayesian networks

X-chromosomal short tandem repeats (X-STRs) are very useful in complex paternity cases because they are inherited by male and female offspring in different ways. They complement autosomal STRs (as-STRs) allowing higher paternity probabilities to be attained. These probabilities are expressed in a likelihood ratio (LR). The formulae needed to calculate LR depend on the genotype combinations of suspected pedigrees. LR can also be obtained by the use of Bayesian networks (BNs). These are graphical representations of real situations that can be used to easily calculate complex probabilities. In the present work, two BNs are presented, which are designed to derive LRs for half-sisters/half-sisters and mother/daughter/paternal grandmother relationships. These networks were validated against known formulae and show themselves to be useful in other suspect pedigree situations than those for which they were developed. The BNs were applied in two paternity cases. The application of the mother/daughter/paternal grandmother BN highlighted the complementary value of X-STRs to as-STRs. The same case evaluated without the mother underlined that missing information tends to be conservative if the alleged father is the biological father and otherwise nonconservative. The half-sisters case shows a limitation of statistical interpretations in regard to high allelic frequencies.     

Agonal sequences in a filmed suicidal hanging: analysis of respiratory and movement responses to asphyxia by hanging

The forensic literature on the pathophysiology of human hanging is still limited. Therefore, forensic pathologists often feel uncomfortable when confronted with related questions. Here presented is the filmed suicidal hanging of a 37-year-old man. This recording allows a unique analysis of agonal movement sequences: loss of consciousness (13 sec), convulsions (15 sec), decortication rigidity (21 sec), decerebration rigidity (46 sec), second decortication rigidity (1 min 11 sec), loss of muscle tone, (1 min 38 sec) and last isolated muscle movement (4 min 10 sec). As for respiratory responses, very deep respiratory attempts started at 20 sec. Respiratory movements progressively decreased and completely stopped at 2 min. Despite the fact that extending the presented data on all cases of hanging asphyxia would be a mistake, this case gives a very interesting insight into movement and respiratory response to asphyxia by hanging.     

STR typing of ancient DNA extracted from hair shafts of Siberian mummies

The aim of this study was to determine if ancient hair shafts could be suitable for nuclear DNA analysis and to develop an efficient and straightforward protocol for DNA extraction and STR typing of ancient specimens. The developed method was validated on modern and forensic samples and then successfully applied on ancient hairs collected from Siberian mummies dating from the 16th to the early 19th centuries. In parallel extractions including or excluding a washing step were performed at least two times for each sample in order to evaluate the influence on the quantity of nuclear DNA yielded and on the typing efficiency. Twelve ancient individuals were analyzed through our approach and full and reliable profiles were obtained for four of them. These profiles were validated by comparison with those obtained from bone and teeth DNA extracted from the same ancient specimens. The present study demonstrates that the washing step cannot be considered as deleterious for DNA retrieval since the same results were obtained by the two approaches. This finding challenges the hypothesis that recoverable nuclear DNA is only found on the outer surface of hair shafts and provides evidence that nuclear DNA can be successfully extracted from ancient hair shafts. The method described here constitutes a promising way for non-invasive investigations in ancient DNA analysis for precious or historical samples as well as forensic casework analyses.     

Pattern detection in forensic case data using graph theory: application to heroin cutting agents

Pattern recognition techniques can be very useful in forensic sciences to point out to relevant sets of events and potentially encourage an intelligence-led style of policing. In this study, these techniques have been applied to categorical data corresponding to cutting agents found in heroin seizures. An application of graph theoretic methods has been performed, in order to highlight the possible relationships between the location of seizures and co-occurrences of particular heroin cutting agents. An analysis of the co-occurrences to establish several main combinations has been done. Results illustrate the practical potential of mathematical models in forensic data analysis.     

Establishing identity using cheiloscopy and palatoscopy

Establishing a person's identity can be a very difficult process. Dental, fingerprint and DNA comparisons are probably the most common techniques used in this context, allowing fast and secure identification processes. However, since they cannot always be used, sometimes it is necessary to apply different and less known techniques. In this paper, the authors describe two unusual techniques: cheiloscopy and palatoscopy. It is known that due to their special features, both lip grooves and palatal rugae can be used successfully in human identification. This paper reviews the techniques of cheiloscopy and palatoscopy, and describes the different classifications and their advantages and limitations.