Opinion ID: 2600593
Heading Depth: 6
Heading Rank: 3

Heading: Blood on defendant's shirt

Text: Criminalist Lough performed a test on a spot of blood one millimeter in diameter located on the neck of a shirt found in defendant's apartment, to determine whether five different genetic markers were present. Lough was able to extract only one genetic markeridentified as a PGM 1 subtype because the sample was very small. That subtype appears in approximately 40 percent of the population. The genetic marker matched Tahisha's blood, but did not match defendant's blood. Criminalist Stockwell tested a second spot of blood, which appeared on the upper left front of the shirt and measured several millimeters in diameter. Stockwell analyzed two genetic markers identified as GM/KM (or gamma marker and kappa marker). These two markers are independently inherited, and they provide useful statistics by which to distinguish among various population groups. Among the three racial groups that comprise the majority of San Bernardino CountyCaucasians, African-Americans, and Hispanics the type of GM protein in the bloodstain never appears among Caucasians or Hispanics, but appears in approximately three of every 1,000 individuals of African-American ancestry, including those having mixed-race ancestry. Because the GM protein in the bloodstain excluded Caucasians and Hispanics as possible sources, Stockwell considered the frequency of the bloodstain's type of KM protein among the African-American population. This type of KM protein found in the bloodstain occurs in 44.9 percent of individuals with African-American ancestry, including those having mixed-race ancestry. These results excluded defendant, who is Caucasian, as a source of the bloodstain. These two factors matched Tahisha, whose father is African-American and whose mother is Caucasian. Although the type of testing performed in 1993 required use of the entire bloodstain, after that testing there remained cellular material that had adhered to the fabric. This material was saved in anticipation of advances in testing technology. In 1996, Stockwell was able to test seven locations on the DNA for genetic markers that are independently inherited. [10] Each of the seven markers matched Tahisha's blood. Stockwell calculated that the frequency with which someone with this genetic profile would appear in that population is one in 400 million.