An experimental study on human bitemarks digital analysis and its accuracy / 生物医学工程学杂志

This experiment was designed to study the method of human bitemarks digital analysis and its accuracy. The human bitemarks were made on the dog skin by human dentition. The related parameters of human bitemarks and suspects criminal dentitions were digitally recorded and managed. The digital picture of human bitemark was obtained, and the dental study model, bite in wax and bitemark on pig skin of suspected criminal were scanned. The overlay was prepared with Adobe Photoshop 5. 5 and the parameters were measured with AutoCAD R14, then their matches were compared. The result shows that the human bitemarks digital analysis is a more accurate approach to human bitemarks identification. Three methods for collecting evidence dental study model, bite in wax and bitemark on pig skin all can be used as aids in forensic sciences. Dental study model is the most accurate one of all the three methods mentioned above.

A biomechanical study on the morphological changing process of human bitemarks / 生物医学工程学杂志

This is a biomechanical research in the morphological changing process of human bitemarks on the skin of dogs. The human bitemarks were made on the live and dead dogs by different tooth and occlusal force. The changing process of the bitemarks were recorded for a long time and its related morphological parameters were measured. Then multiple stepwise regression analysis was made to disclose the relationship of the shape of the bitemarks to occlusal force, time, and tooth area, tooth width and thickness. The mathematic relationship of the morphological changing process of the bitemark with occlusal force, time and tooth shape was established.

The blind assessment of human bitemarks by digital analysis / 中国法医学杂志

Objective Digital analysis of human bitemarks by blind method was assessed for its accura-cy. Method Digital analysis was used in double-blind method for identification of human bitemarks with control samples from 8 suspects. Photoshop 5.5 generates an overlay from bitemarks scanned and various coefficients were submitted for analysis by AutoCAD R14 engineering software to compare bitemarks with denture of suspects. Results Digital analysis shows that bitemarks tally with cast of denture from "suspects" in every coefficient. Conclusion Digital analysis is feasible for identification of experimental bitemarks and promises sound prospects in future forensic practice.

The study on the morphological changes of human bitemark / 中国法医学杂志

Objective To study the morphological changes, human bitemarks were made on the living and dead canine skin. Method The changing patterns of the human bitemarks were recorded with morphological parameters measured. The relationships among the patterns of the bitemark, tooth area, time, ocdusal force, tooth width and thickness were analyzed by multiple progressive regression. Results The multiple progressive regression equations of the morphological changes of human bitemark were established: S=-6.96-1.68?10 2T-0.11F +2.21W+3.75H(Live dog test,T

A study of forensic DNA databases / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>The forensic DNA databases are very important for individual identification. In order to evaluate the genetic markers used for a forensic DNA databases and the compatibility between the manual DNA typing system and the automatic DNA typing system, a testing DNA database should be constructed. Also, constructing a testing DNA database can increase our understanding of the issue for forensic DNA databases.</p><p><b>METHODS</b>A total of 1000 specimens, including samples of blood, blood stains, salvia stains, semen stains, mixture stains and muscle tissues, were collected from the public security bureau of Chengdu. The DNA of each specimen was extracted by Chelex method and analyzed using Amp-FLP technique. A total of 8 STR loci, including D3S1358, D9S1118, vWA, D5S818, D16S539, D8S1179, CSF1PO and D20S161 were chosen and employed for DNA typing. Each STR locus was amplified by the polymerase chain reaction PCR and the PCR products were typed with the polyacryamide gel electrophoresis. Typing DNA was carried out by comparing with a human allele ladder. A total of 8 human allele ladders for D3S1358, D9S1118, vWA, D5S818, D16S539, D8S1179, CSF1PO and D20S161 were made in-house. Managing software of the testing DNA database was designed using Microsoft Access.</p><p><b>RESULTS</b>The results of DNA typing in 1000 specimens showed that the total discrimination power of 8 STR loci was over 0.99999999.</p><p><b>CONCLUSION</b>This study show that a forensic DNA database should be useful for search purpose. The total discrimination power over 0.99999999 imply that in principle there is no identical genotype at whole 8 STR loci between two persons from a population with 10000000 individuals. This means that 8 STR loci used in this study are suitable to construct forensic DNA databases in Chengdu of China. The result of DNA typing can be repeated and the data have compatibility between the manual DNA typing system and the automatic DNA typing system. The data search in our testing DNA database can be carried out using only some loci of the set of 8 STR markers. Also, the volume of our testing DNA databases could be enlarged easily. The implication from this study is that the legislation should not be negligent before establishing a forensic DNA database. This DNA database provides a model for establishing the forensic DNA databases in China.</p>

Forensic application of D20S161 and D8S384 loci / 中国法医学杂志

To evaluate the forensic validation of D20S161 and D8S384 loci.Two typing kits for D20S161 and D8S384 had been home made.The samples had been analyzed by using both kits,which including human blood,human semen,human saliva,animal blood,mixture of human blood and animal blood;human bloodstain,human semen stain,human saliva stain,animal bloodstain, mixture stain of human blood and animal blood; old bloodstains.The sequences of primers for both loci had been compared with 606364 sequences in data base in GeneBank,USA.There are positive results for human blood,human semen,human saliva,mixture of human blood and animal blood by using both kits for D20S161 and D8S384 loci.But animal bloods have not any PCR-productyet.Genotyping of human bloodstain,human semen stain,human saliva stain,mixture stain of human blood and animal blood by using both kits for D20S161 and D8S384 loci were correct.But animal bloodstains had not any PCR productyet.Also, all of fifty old bloodstains had positive results of typing for D20S161 and D8S384.No product was obtained by PCR technigue when primers for both D20S161 and D8S384 loci were tested against 606364 known sequences in the data base in GeneBank.The results demonstrated that both loci have species specificity.Both D20S161 and D8S384 loci are useful marker for forensic casework and paternity analysis.