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Examples of exceptional human identifications done by department of forensic genetics in Szczecin, Poland

Published:October 27, 2015DOI:https://doi.org/10.1016/j.fsigss.2015.09.202
      The research shows example of three identification processes, each with different level of difficulty. Even though all of them used methods typical for forensic genetics, each had to be treated in a very special way.
      First case concerns determination of maternity and paternity of four newborns. Infants were found dead, buried in a garden in a plastic bags. The remains were skeletonized with mortuary wax present. Femur from each newborn was used for a genetic testing. Second case concerns a drowning of a homeless man, whose body was found by a fisherman. Although the ID was present, the family did not affirm man’s identity. Genetic material coming from half siblings (two sisters and two brothers) was used as a reference. For the final identification all the possible analysis had to be done: autosomal STR, X-STR, Y-STR and mitochondrial DNA. The last case concerns a murder of an elderly man. He was killed and then buried with the use of roofing felt. It caused complete reduction to ashes. Meticulous anthropological analysis helped with selecting single bone fragment proper for a genetic testing. The obtained profile was used for the identification and solving the crime.
      The research shows that genetic testing is very useful in a final identification of unknown bodies. In spite of the impact of a various factors of degradation, reliable and repeatable results can be obtained.

      1. Introduction

      The use of DNA analysis in identifications of individuals in many cases is the only possible way of personal identification. Despite using the same research tools, each identification should be approached individually. Sometimes the cases that seem to be a complete failure turned out to be an easiest one, and the cases initially classified as simple may be quite a challenge.

      2. Materials and methods

      2.1 Identification process of four new-borns

      The remains of new-borns were revealed in plastic bags, soft tissues turned into mortuary wax, only small fragments of skin were preserved. After cleaning the bones, for genetic tests one selected one femur of each individual.
      The comparative material came from the alleged mother and father of new-borns babies, owners of the property on which the remains of children were found and from the brother of the alleged father.
      Isolation of genetic material was conducted using PrepFiler® BTA Forensic DNA Extraction Kit, the resulting genetic material was amplified by with two kits NGM, GlobalFiler and mtDNA sequencing was additionally performed.

      2.2 Identification process of a homeless man found in the river

      During the carried out autopsy, for identification tests a fragment of muscle was collected. The comparative material came from two half-brothers and two half-sisters. NN man had a different father than the other four siblings.
      The isolation of genetic material was performed using PrepFiler kit. Amplification was performed using four kits: NGM™, MiniFiler™, Yfiler and Investigator Argus X-12 Kit, additionally mitochondrial DNA sequencing was performed.

      2.3 Identification process of a man burned in fire

      From the remains of a man revealed in the burning out fire for about 2000 different sized bone remains of a human skeleton were selected with a total weight of about 2 kg. A comparative study of DNA two bone fragments which did not succumb to the complete burnout were selected: a fragment of the cranial vault and lumbar vertebra. The material for the comparative study came from the alleged sister and son.
      The isolation of genetic material was performed using PrepFiler kit. Amplification was performed using two kits GlobalFiler and Yfiler.

      3. Results and discussion

      The femurs from four new-borns turned out to be the most difficult research material. At least three isolations from each femur were performed, but amplification kit NGM failed. The isolates were to re-amplified with GlobalFiler kit, with this kits the complete profiles were obtained and the degree of probability of paternity and maternity was increased. During the investigation, the prosecutor’s office suspected that the brother of the alleged father can be the biological father of one of four new-borns, however, the analysis of genetic profiles has not confirmed this hypothesis.
      Process of identification of the homeless man the biggest difficulty was caused by distant relationship between the victim and the reference samples. Although a short period of time has passed from drowning to revealing the body, the family has not been able to identify the corpse. In addition, an ID card was found with the body. Our task was only to confirm the identity of the man. At the beginning of the identification process we had only comparative material collected from two brothers of the unknown man. The results of autosomal STR analysis showed incompatibility in the three markers, which in the case of siblings is not unusual, but compatibility of y-STR between the brothers and the unknown man was not obtained. Only after consultation with the prosecutor we obtained information about the fact that men have different fathers. After a few days, we were provided with additional comparative material from two half-sisters. The test results for autosomal STR were similar as in case of the brothers. Next, a test on the markers located on chromosomes X was performed, however, the results also did not give a final settlement. Finally, mitochondrial DNA test was performed, the resulting haplotypes were identical for all five siblings.
      In matters of distant kinship one can have recourse to the victim's personal belongings, but in this particular case the man was homeless, and therefore obtaining a profile with personal belongings was impossible. Comprehensive research results enabled to confirm with a high probability the identity of the man.
      The seemingly extremely difficult research material consisting in almost completely burnt remains of a man has given unexpected good results. In each of the samples taken, after the first isolation complete DNA profile was obtained, both in the Global filer and Yfiler kit. In this particular case, obtaining complete profiles, despite such an advanced degree of burning of debris did not cause any problem. Molecular studies and comparative analysis of the obtained profiles allowed for fast identification.

      4. Conclusion

      • 1.
        Degraded biological material should be collected by forensic geneticist with the participation of the court physician/anthropologist in order to select the best preserved fragments for DNA testing.
      • 2.
        The presence of forensic geneticist during sampling for DNA testing greatly minimizes the risk of contamination.
      • 3.
        In the analysis of distant kinship as broad as possible spectrum of identification markers should be used.