[Chronology of a homicide and an attempted suicide by DNA analysis of selected blood stains on the weapon (knife)]].
A five-year-old boy was fatally injured by a stab and a cut to the throat. The suspected offender, an acquaintance of the victim's mother, stated that he had been disturbed by the boy while attempting suicide and had therefore killed the boy. The suspect showed superficial cuts on both wrists and three shallow stabs on the right-hand side of the abdomen. The purpose of the forensic investigations was to answer the question if the suspect's statement could be confirmed or if the attempted suicide took place after killing the boy. The blood-smeared blade of the knife was divided into different sectors with the cutting edge and the tip of the blade being examined separately from the sides. The blood traces from the different blade sectors were then typed in 12 different DNA regions by PCR (polymerase-chain-reaction). It could be demonstrated that the strong blood traces on the sides of the blade originated from the victim alone, whereas in the area of the edge and the tip of the blade the amount of the victim's blood was negligible compared with that of the suspected offender. The explanation for this finding is that in the areas of the edge and the tip of the knife the blood of the victim must have been replaced by the blood of the suspected perpetrator, which means that the suicidal injuries were the last to be caused by the knife.
Förster
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Kriminaltechnischen Institut, Landeskriminalamtes Baden-Württemberg.
D000328:Adult; D001134:Arm Injuries / Q000097:blood*; D001798:Blood Proteins / Q000235:genetics; D001801:Blood Stains; D002675:Child, Preschool; D006708:Homicide / Q000331:legislation & jurisprudence*; D006801:Humans; D008297:Male; D019838:Neck Injuries / Q000097:blood*; D016133:Polymerase Chain Reaction; D013406:Suicide, Attempted / Q000331:legislation & jurisprudence*; D013997:Time Factors; D014951:Wounds, Stab / Q000097:blood*
D001798:Blood Proteins