Abstract
This report is a case in which some bloodstains found in a crime scene were A3B variant of the ABO blood group. A man was killed in a car and thrown into the sea. Five months later, several bloodstains were discovered in the car where he was killed. The reaction of those bloodstains by the absorption-elution test showed that A-antigenicity was much weaker than B-antigenicity. Therefore, it could not be decided whether the blood type of the bloodstain was AB or B. We investigated to get information about his blood type, because the blood group of the bloodstain were inexplicable. In the postmortem, his blood type and the characteristic of his teeth had been investigated to confirm him. It was estimated that his blood type was AB by the results of the absorption-elution test using decayed blood in his thoracic cavity.
On the other hand, his ABO genotyping was judged to be AB type by gene analysis using DNA of the pulp of a tooth. Also, his blood type was AB, exarmined using the blood from the hospital. These information could not convince us, and we further investigated his blood type. As a result, we found that his blood group had been elucidated to be an A3B type at a hospital that he was hospitalized at in the past. It was found that the cause of the indefinite blood type reaction was a variant.
