Forensic identification of urine samples: a comparison between nuclear and mitochondrial DNA markers.

Urine samples from 20 male volunteers of European Caucasian origin were stored at 4 degrees C over a 4-month period in order to compare the identification potential of nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) markers. The amount of nDNA recovered from urines dramatically declined over time. Consequently, nDNA likelihood ratios (LRs) greater than 1,000 were obtained for 100, 70 and 55% of the urines analysed after 6, 60 and 120 days, respectively. For the mtDNA, HVI and HVII sequences were obtained for all samples tested, whatever the period considered. Nevertheless, the highest mtDNA LR of 435 was relatively low compared to its nDNA equivalent. Indeed, LRs obtained with only three nDNA loci could easily exceed this value and are quite easier to obtain. Overall, the joint use of nDNA and mtDNA markers enabled the 20 urine samples to be identified, even after the 4-month period.

Forensic evaluation of the QIAshredder/QIAamp DNA extraction procedure.

The potential to recover genetic profiles from evidence samples has substantially increased since robust and sensitive amplification kits are commercially available. Nevertheless, even the best amplification kits cannot succeed when the extracted DNA is of poor quality. In this study we compared the efficiency of silica (QIAamp DNA Mini Kit), Chelex and Phenol-Chloroform (PC) based protocols to recover DNA from different categories of samples (blood and saliva on cotton swabs, muscles, cigarette butts, saliva on foods and epidermal cells on clothes). The efficiency of the QIAamp system was improved when samples were treated with QIAshredder homogenizing columns. Overall, conventional Chelex or PC protocols allowed to recover conclusive SGM Plus profiles for 61% of the samples considered in this study. Contrastingly, 82% of them were successfully genotyped after being treated with a combination of QIAshredder and QIAamp systems. Our results further suggested that the QIAshredder/QIAamp protocol was particularly helpful to analyze evidence samples with few DNA and/or that were collected on substrates containing PCR inhibitors.

Tunisian population data on 10 Y-chromosomal loci.

Alleles and haplotypes frequencies for 10 Y-chromosome STR loci (DYS19, DYS385 I/II, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS438 and DYS439), included in the Y-Plex6 and Y-Plex5 kits were determined for a Tunisian population sample of 100 male individuals.

A case of suicide disguised as natural death.

A case report describing the suicide of a physician classified initially as a natural death. Faced with the vehement protest of the family of the deceased the magistrate decided to request a 'preventive' forensic autopsy. Forensic investigations revealed the cause of death as being a pentobarbital intoxication and the circumstances favoured the hypothesis of a genuine suicide. This case illustrates that the tendency of magistrates to request or not an autopsy is related to their experience or intuition.

Tunisian population data on 15 PCR-based loci.

Genotype and allele frequencies distribution for 15 PCR-based loci included in the Promega PowerPlex 16 kit were determined for a Tunisian population sample of 196 unrelated individuals.

Sudden death related to small coronary artery disease.

Two cases of sudden death of young people in apparently good health are reported. The only pathologic change found was a fibromuscular dysplasia of the artery supplying the conduction system of the heart with an important narrowing of the lumen and strong thickening of the arterial wall. The first case was of a 12-year-old girl who died suddenly while skiing; the second was of a 32-year-old man who died while talking to his wife. No other pathologic changes were found at autopsy, and the results of toxicologic analysis were negative. There was no individual or family history of cardiac diseases. These cases illustrate the importance of an analysis of the conduction system, including examination of the intramural coronary arteries supplying the conduction system.

The reconstruction: a useful tool in forensic sciences.

The intervention of a forensic pathologist may be required at any stage of a judicial investigation. Clearly, he or she plays an important role at a crime scene and later on during the examination of the body. But the forensic pathologist's contribution is equally important during reconstruction, which is most frequently called for in cases of violent deaths, homicides in particular. However, reconstruction may also be very useful in cases of less importance in terms of criminal law. It requires little investment and can provide precious evidence. In the two cases presented here we were able to exclude, respectively, the presumption of the adulteration of a blood sample taken for alcohol dosage and the accidental origin of an attempted murder. In fact, reconstruction may be a valuable procedure in any event requiring the participation of a forensic expert.

The challenge of identification following the tragedy of the Solar Temple (Cheiry/Salvan, Switzerland).

On October 5, 1994, 48 members of the Sect of the Solar Temple were found dead at two different locations in Switzerland: 23 victims in Cheiry and 25 victims in Salvan. Our Institute was commissioned to solve the forensic problems presented by this tragedy. Our goals were to establish the time of death, determine its causes, help elucidate the surrounding circumstances and identify the victims. This work presented us with the following challenges. This catastrophe was of an 'open' type: there was no list of 'passengers'; the victims were of five different nationalities and many had just arrived in Switzerland to participate in this event; family ties were very complex within this group; half of the victims were burned and sometimes charred; the exceptionally intense media converage of the story put a lot of pressure on the investigators and our Institute. In spite of these difficulties, all the victims were positively identified within 1 month. In the present report, we describe the steps realized to progress in our work. A special section describes our relationship with the journalists and their invaluable help in our investigations. The importance of being prepared for such an event is discussed.

Forensic evaluation of mtDNA in a population from south west Switzerland.

The polymorphism of the two hypervariable segments (HVI and HVII) of the control region of mtDNA was analyzed in a population of 154 unrelated individuals from south west Switzerland using a fluorescent based capillary electrophoresis sequencing method. In our population data of 154 random individuals, 137 mtDNA types were observed. Of these, 124 sequences were observed only in one individual whereas 10 sequences were observed in 2 individuals, 2 sequences in 3 individuals and 1 sequence in 4 individuals. The probability of two unrelated individuals having the same sequence was 0.84%. The results were compared with four other Caucasian populations. Furthermore, the usefulness of the mtDNA sequencing was tested, for exclusion and inclusion, in 18 forensic cases including 69 evidence samples and 44 reference samples. Despite the fact that 55% of the evidence samples yielded a negative result for the nuclear DNA with the human dot quantitation system, the success rate of the mtDNA sequencing was 71.0%. This validation study proves the great usefulness and sensitivity of the mtDNA sequencing technique using nested PCR and fluorescent capillary electrophoresis.

Forensic validation of the short tandem repeat HUMACTBP2 using capillary electrophoresis.

Experiments were performed to evaluate the forensic identification of the short tandem repeat (STR) HUMACTBP2 (human beta-actin-related pseudogene) using automated fluorescence-based capillary electrophoresis. The HUMACTBP2 is a complex tetranucleotide STR locus with more than 32 alleles in the range of 202-323 bp. The reproducibility of genetic typing using a fluorescent labeled allelic ladder was determined by comparison of the calculated fragment size after consecutive (within-day) and nonconsecutive (day to day) injection. The maximum variation in size (window) observed for any allele was 0.23 bp for the within-day and 0.8 bp for the day-to-day precision. Furthermore, it is possible to achieve a 1 bp resolution, the precision of the reproducibility assays being about 99.95%. Sixty blood samples and twenty stains were typed with both automated fluorescent sequencer ABI 373A and ABI 310. Identical genotypes were obtained with both techniques and the ABI 310 seemed to be more sensitive than the ABI 373A. A population sample of 197 unrelated individuals from southwest Switzerland was analyzed and the genotype frequencies observed were similar to those reported by others. Thirty-one alleles and 126 genotypes were found. The observed heterozygosity was 0.934. Mixtures from two different blood samples varying in their ratio were typed and the minor fraction was detectable to about 1:10. The practical usefulness of the HUMACTBP2 is illustrated by analyzing casework samples. This validation study proves the usefulness of the HUMACTBP2 locus in forensics and the detection efficiency using fluorescent capillary electrophoresis.

PCR-based forensic testing of DNA from stained cytological smears.

Experiments were performed to evaluate the efficiency of PCR-STR (Short Tandem Repeats) and PCR-sequence polymorphisms for the identification of stained pap smears and postcoital slides stained with cytological and forensic techniques. HLA-DQA1, PolyMarker, Amelogenin, HUMTH01, HUMVWFA31, HUMF13B, and HUMFES/FPS were determined. With the exception of the forensic Baecchi stain, all the PCR-systems gave consistent results in comparison with the reference blood from the donors. Cytological stained smears can be important evidence for identification in sexual assault cases and in missing person cases.

F13B and CD4 allele frequencies in south west Switzerland.

Allele frequencies of the two short tandem repeat (STR) systems F13B and CD4 were determined in a population sample from South West Switzerland using PCR analysis. We found five alleles for both STRs in a population sample of 205 unrelated individuals. No significant deviation from Hardy-Weinberg equilibrium was observed.

Evaluation and usefulness of reverse dot blot DNA-PolyMarker typing in forensic case work.

Experiments were performed to evaluate the Amplitype PolyMarker DNA typing system for application to forensic casework. DNA extraction using chelex was compared with phenol-chloroform extraction for various biological materials including postmortem blood, blood samples used for alcohol quantification, fresh urine, envelopes and cigarette butts. Different amounts of genomic DNA were amplified to test the sensitivity of the Amplitype PM. Mixed samples of two different bloods were typed to determine the dilution at which mixtures could be detected. Different storage conditions were evaluated using urine samples. Postmortem blood samples were typed during 4 months to determine the effects of natural degradation. A population sample of 105 unrelated individuals from South-West Switzerland was analyzed and the genotype frequencies were compared with those reported by others. Finally, practical usefulness of the Amplitype PM system is illustrated by analysing casework samples. The results of this validation proved the great usefulness and sensitivity of the Amplitype PM system using the appropriate extraction and typing method. However, mixed samples had to be interpreted with caution owing to the possibility of non-specific alleles with stored material such as urine and postmortem blood.

Isérables: a Bedouin village in Switzerland?

Isérables is an alpine village--about 1000 inhabitants--which remained isolated till these recent years because of its particular geographical situation. The Isérables inhabitants call themselves "Bedjuis" (Bedouin in local dialect) and regard themselves as descendants of the Sarrazins who invaded the Alps during the VIII-X centuries. Our goal, in studying several DNA-VNTR polymorphims, in addition to some blood groups, within the Isérables community, was to see if there was any evidence supporting this popular belief. As a preliminary phase of this project, the allelic frequencies for six VNTR loci analysed for 102 individuals of the village (all descendants of nine original families) are presented. The results are compared with those reported for Swiss and white populations.

Chemiluminescent DNA probes: evaluation and usefulness in forensic cases.

Five phosphatase-labelled oligonucleotide probes were evaluated in respect to their sensitivity, with the help of an optimized chemiluminescent protocol, for DNA-VNTR polymorphism determination. Their usefulness for the identification of biological traces is illustrated with casework examples.

An unusual case of sudden death in an alcohol addict.

The sudden and unexpected death of a 40-year-old female alcohol addict is described. At the autopsy recent rib fractures were found. The extremity of one fractured rib had caused a massive haemorrhage by erosion of a coronary artery.

Simultaneous phenotyping of erythrocyte acid phosphatase and esterase D by nonequilibrium agarose isoelectric focusing.

Nonequilibrium agarose isoelectric focusing in a pH 4.5-7 gradient with 3-(N-morpholinopropanesulfonic acid (MOPS) and taurine as chemical separators presents a fast, easy and reliable method for the simultaneous determination of the common erythrocyte acid phosphatase and esterase D phenotypes in hemolysates and dried bloodstains. The application of the method to experimental and casework bloodstains is described.