Abstract
In a series of random murders and gang rapes, biological material left at the crime scene was often a mixture from two or more individuals. In such cases, it is difficult to identify the DNA profile of each individual. Therefore, using the MCAR method, we aimed to detect the individual components of such a mixture for DNA typing, thereby establishing a method of examination that facilitates personal identification from a mixture of biological samples.
In this study, we attempted to establish a method for the preparative separation of cells using laser microdissection (LMD), and determined the number of cells required for DNA typing. In addition, we investigated whether it is possible to determine the DNA profile of the cells separated from an experimental mixture of blood.
As a result, we found that at least 16 cells were required for DNA typing by cell smear-LMD method. On the other hand, 150 cells were need for DNA typing by cell transfer-LMD method. In the case of a mixture of blood group A and B cells, it was possible to determine the DNA profile of each individual by the preparative separation of cells in positive regions with anti-A or anti-B antibody using MCAR and LMD.
Biological material at the crime scene is almost always collected on a piece of gauze or adhesive tape, and for these cases, it is necessary to use the cell transfer method. In this study, it was suggested that the cell transfer-LMD method was expected in forensic application.
However the mixtures are variously mixed with a great variety of cases for every sample, and are on various carriers. So we need to identify the exact location of the individual component and to take notice of biological contamination on carriers.
