Opinion ID: 1215480
Heading Depth: 2
Heading Rank: 2

Heading: The Medical Experts' Testimony

Text: Dr. Edward Blake, a forensic serologist, conducted tests on semen found in Hill's vagina, as well as on her blood. Prior to any testimony by Dr. Blake before the jury, defense counsel requested a foundational hearing pursuant to Evidence Code section 402. The record does not show the request or whether any objection or offer was made in connection with the request. [1] After the section 402 hearing, the only objection defendant made to Dr. Blake's testimony was that he should have performed a test in addition to those tests that were performed. At the Evidence Code section 402 hearing, the prosecutor did not question Dr. Blake or otherwise attempt to lay a foundation for his testimony. Dr. Blake's testimony at the hearing was largely repeated at trial, and the following summary of Dr. Blake's testimony includes that given at the hearing and before the jury. Blake has a doctorate in criminology from the University of California at Berkeley. He wrote his doctoral dissertation on the determination of genetic markers in human semen. He has also published numerous articles on the subject. Blake received a vaginal wash of Shirley Hill from Dr. Stephens of the coroner's office. Blake testified that a vaginal wash is generally obtained by inserting a saline solution into the cavity and then withdrawing it into a syringe. [2] He also obtained a sample of Hill's blood, and blood and saliva samples from her former husband and from defendant. Tests performed showed that the semen found in the vaginal wash could not have been her former husband's, and that defendant was a member of a class consisting of 8 percent of the population that could have deposited the semen. [3] Blake explained the two tests he used to classify the bodily substances he had received. The first test used can identify, in some instances, the blood type of a person by the antigens found in bodily fluids other than blood. Blake explained that every person has one of four possible blood antigen types  A, B, AB or O. Most people (80 percent of the general population) secrete their antigens into other bodily fluids such as saliva, semen, urine and vaginal secretions. Thus the blood type of secretors can be determined by examination of one of these fluids. The vaginal wash obtained from Hill's body, although it contained a high level of semen, did not contain any blood antigens, indicating that the semen donor was one of the 20 percent of the population that does not secrete antigens  a nonsecretor. [4] Blake also did an analysis of PGM in the semen sample. PGM analysis categorizes an enzyme found in every person's bodily fluids and secretions; the various types have been found to occur with established frequencies in the population. There are three PGM groups: 1/1, 2/1 and 2/2. PGM types 2/1 and 2/2, together, occur in 40 percent of the population. Decedent's blood was type 1/1; the vaginal wash contained type 2, which, then, must have come from the semen donor. Defendant proved to be a type O nonsecretor (so that his blood antigens would not have been found in the wash), PGM type 2/1. According to Blake, because only 20 percent of the general population are nonsecretors and 40 percent of the general population are PGM type 2/1 or 2/2, statistically only 8 percent of the general population could have donated the semen found in Hill's body. Blake testified that these are established statistical frequencies, not projected possibilities. A frequency computation is valid only where the variables (secretor-nonsecretor and PGM type 1/1, 2/1 or 2/2) are independent, as these are. In other words, there is (and must be) no preexisting relationship between antigen secretors and any particular PGM type. Studies have shown that the frequency of PGM 2 is the same among secretors and nonsecretors. Further, for the frequency calculation to be valid, the characteristic must be stable at all times in the subject. Here, both tests looked for genetic traits or markers which do not change, but remain constant through life. Defendant presented testimony directed to the medical evidence other than the tests performed by Dr. Blake. A defense investigator stated that he had talked with Sisson, a doctor in the coroner's office, who had stated that the medical evidence was not inconsistent with consensual sexual intercourse, and that the presence of sperm in the victim's rectal cavity could be present for reasons other than sodomy. Sisson was also reported as having been surprised that a Peptidase A test was not done on the vaginal wash. The defense also called Dr. Jindrich, the Marin County Coroner and a forensic pathologist, who testified that sperm in the rectal area was not necessarily indicative of sodomy, in that it could have been caused by leakage from the vagina after intercourse or as the result of the movement of the body by the coroner's office. Also, because there was no damage to the vagina, perineum or rectum, it was not clear that the intercourse was not consensual; the other abrasions on the body could have been caused by Hill's struggle with her killer, or by rough handling of the body by the coroner's employees. Jindrich did agree that because the semen deposits were both four or five inches inside two different cavities, and there was no staining of the clothing or leakage onto other areas of the body, it was likely that there had been two separate deposits of semen, rather than leakage from one area to another. As previously indicated, the jury found defendant guilty of first degree murder with special circumstances, and other lesser offenses.