Linking a bloodstain to a missing person by genetic inheritance

The use of the principles of genetic inheritance to link a bloodstain to a missing victim is discussed. Genetic marker typing can determine whether the parents of the missing victim are possible parents of the bloodstain source. Given a parental inclusion, it is possible to calculate the probability that a randomly selected couple would possess the necessary genetic combinations to be the parents of the person who bled. The applications of this concept using several genetic marker systems are examined. General formulas have been developed for the probability calculation using phenotype distribution frequencies and gene frequencies. This approach was applied to a homicide case in which it was shown that the victim's parents were among only 0.8% of couples from the general population who would be able to bequeath the genetic marker types found in the bloodstain. This evidence was helpful in producing a conviction of first degree murder.