People v. Wilson

• Decision Date: 06 July 2006
• Docket Number: No. S130157.,S130157.
• Citation: 45 Cal.Rptr.3d 73,38 Cal.4th 1237,136 P.3d 864
• Court: California Supreme Court
• Parties: The PEOPLE, Plaintiff and Respondent, v. William Curtis WILSON, Defendant and Appellant.

45 Cal.Rptr.3d 73

38 Cal.4th 1237

136 P.3d 864

The PEOPLE, Plaintiff and Respondent, v. William Curtis WILSON, Defendant and Appellant.

No. S130157.

Supreme Court of California.

July 6, 2006.

Victor J. Morse, San Francisco, under appointment by the Supreme Court, for Defendant and Appellant.

Bill Lockyer, Attorney General, Robert R. Anderson, Chief Assistant Attorney General, Gerald A. Engler, Assistant Attorney General, Stan M. Helfman, Enid A. Camps and Sharon G. Birenbaum, Deputy Attorneys General, for Plaintiff and Respondent.

CHIN, J.

[136 P.3d 1239]

This murder case presents a narrow, but important, question regarding the admissibility of deoxyribonucleic acid (DNA) evidence to prove identity in criminal prosecutions. A DNA comparison of blood found at the crime scene with defendant's blood resulted in a match. That is, defendant's genetic profile matched that of the blood at the crime scene so that he could not be excluded as a donor of that blood. Similarly, a DNA comparison of blood found on defendant's pants when he was arrested with the victim's blood resulted in a match, so that the victim could not be excluded as a donor of that blood. Obviously, evidence tending to show that defendant's blood was found at the crime scene, and that the victim's blood was on defendant's pants, would be highly probative to whether defendant was the killer.

When a match is found, the next question is the statistical significance of the match. Of course, a match is less significant if the blood could have come from many persons rather than from only a few. Experts calculate the odds or percentages—usually stated as one in some number—that a random person from the relevant population would have a similar match. The question here revolves around exactly what is the relevant population. The question is complicated by the fact that the odds vary with different racial and ethnic groups. Because of this variation, separate databases are maintained for different population groups, and the odds for each group are calculated

[136 P.3d 1240]

separately. In this case, as in many cases, no evidence exists of the racial or ethnic identity of the perpetrator other than evidence indicating that defendant was the perpetrator. Over defense objection, the trial court permitted the prosecution to present evidence of the odds as to the three most common population groups in this country—Caucasians, African-Americans, and Hispanics. For example, the evidence showed that only one Caucasian in 96 billion would match the crime scene blood that matched defendant's profile.

Defendant contends the court erred. Relying heavily on the opinions in People v. Pizarro (1992) 10 Cal.App.4th 57, 12 Cal.Rptr.2d 436 (Pizarro I), and especially, People v. Pizarro (2003) 110 Cal. App.4th 530, 3 Cal.Rptr.3d 21 (Pizarro II), he argues that evidence regarding any particular population group is irrelevant absent independent evidence that the perpetrator was a member of that group. The Court of Appeal concluded that the trial court correctly admitted the evidence. We agree. As Justice Parrilli, author of the majority opinion below, stated, "When the perpetrator's race is unknown, the frequencies with which the matched profile occurs in various racial groups to which the perpetrator might belong are relevant for the purpose of ascertaining the rarity of the profile."

I. FACTS AND PROCEDURAL HISTORY

Around 6:15 p.m. on April 6, 2000, the body of 13-year-old Sarah Phillips was found on the living room floor of her Vacaville home. She had been strangled with a telephone cord, and her body had suffered multiple bruises, scrapes, and scratches. Her pants and panties had been removed, and her shirt was pushed up.

Defendant was arrested around 2:00 a.m. on the morning after the killing and charged with her murder. He had visited the victim's house regularly while dating her older sister three years earlier. DNA evidence as well as other evidence implicated him as the perpetrator. The Court of Appeal summarized the non-DNA evidence: "[Defendant] aggressively propositioned several women before the assault on Sarah, showing interest in whether they lived alone; he admitted speaking with Sarah around the time of the killing when she was alone at her home, where the killing occurred; he was seen by witnesses in the area before the killing, without scratches, and after the killing, with scratches consistent with the struggle indicated by the crime scene evidence; and shortly after the murder he told a witness he had done something bad, which he could not `fix.'"

[136 P.3d 1241]

The prosecution also presented DNA evidence. Three kinds of DNA tests (D1S80, DQA1 polymarker, and STR) were performed on bloodstains found on the victim's clothing and on defendant's clothing when he was arrested. All of the tests matched defendant's genetic profile to blood on the victim's jeans, and the victim's profile to blood on defendant's pants. The STR testing also matched the victim to a hair found in defendant's pants, and both the victim and defendant to blood found under the victim's fingernail.

The STR test was the most sensitive. It compared nine genetic markers and included a marker for gender discrimination. Nicola Shea, a criminalist with the Sacramento laboratory of the California Department of Justice (Department), was the prosecution's STR expert. She testified that, to help juries understand the significance of a DNA match, the Department followed the statistical approach recommended by a 1996 report of the National Resource Center for presenting the frequency with which genetic profiles occur. (Nat. Resource Center, The Evaluation of Forensic DNA Evidence (1996) (hereafter 1996 NRC Report).) The Department used databases that the Federal Bureau of Investigation published in the Journal of Forensic Sciences reflecting profile frequencies in the Caucasian, Hispanic, and African-American populations, "because those are the major populations in our country and in our state."

Shea testified she used all three databases to avoid making assumptions about the ethnic background of the perpetrator. Data for other groups, such as Native Americans, would also be compared if information had indicated another group might be a source of the evidence sample—for example, if the crime had occurred on an Indian reservation. She explained that "the same profile will show up with a different frequency in the different populations." However, she also said that "the three populations given give you a ballpark of how often you would expect to see that profile in those populations. If something is extremely rare in those three populations, you might expect it for that many markers to be extremely rare in one of the other populations." When nine genetic markers are used in the analysis, the result would be a "pretty discriminating number" no matter what population database was used.

Defendant's genetic profile would be expected to occur in one of 96 billion Caucasians, one of 180 billion Hispanics, and one of 340 billion African-Americans. The victim's genetic profile would be expected to occur in one of 110 trillion Hispanics, one of 140 trillion Caucasians, and one of 610 trillion African-Americans. Criminalist Shea noted that these profiles were extremely rare; the world contains only about six and a half to seven billion human beings.

[136 P.3d 1242]

Defendant objected to the introduction of these profile frequencies, arguing that the prosecution had failed to lay a foundation for this evidence because it did not establish the race of the persons who left the blood samples. The trial court disagreed and admitted the evidence. The jury found defendant guilty of first degree murder with use of a dangerous weapon during the commission of an attempted rape and a lewd act on a child.

Defendant appealed. The Court of Appeal found that the trial court properly admitted the DNA evidence and affirmed the judgment. We granted review to resolve a conflict between this opinion and Pizarro II, supra, 110 Cal.App.4th 530, 3 Cal.Rptr.3d 21.

II. DISCUSSION

"DNA analysis . . . is a process by which characteristics of a suspect's genetic structure are identified, are compared with samples taken from a crime scene, and, if there is a match, are subjected to statistical analysis to determine the frequency with which they occur in the general population." (People v. Barney (1992) 8 Cal. App.4th 798, 805, 10 Cal.Rptr.2d 731.) "[O]nce analysis and comparison result in the declaration of a `match,' the DNA profile of the matched samples is compared to the DNA profiles of other available DNA samples in a relevant population database or databases in order to determine the statistical probability of finding the matched DNA profile in a person selected at random from the population or populations to which the perpetrator of the crime might have belonged." (People v. Soto (1999) 21 Cal.4th 512, 518, 88 Cal.Rptr.2d 34, 981 P.2d 958.)

As the Court of Appeal in this case explained, "Profile frequencies within the major racial groups in the United States (Caucasian, African-American, Hispanic, East Asian, and Native American) vary to such an extent that separate DNA databases are maintained for the purpose of providing accurate estimates of profile frequency. (1996 NRC Rep., pp. 28, 57-58, 98, 151; see also People v. Soto, supra, 21 Cal.4th at p. 526, fn. 18, 88 Cal.Rptr.2d 34, 981 P.2d 958.)" (Fn.omitted.) The question here is which, if any, of these databases are relevant when the racial identity of the persons who left the test samples is unknown.

The trial court permitted the prosecution to present evidence of profile frequency within the three most common populations in this state and country—Caucasian, Hispanic, and African-American. Defendant contends that because no independent evidence exists that the donor of the blood samples at the crime scene and on his pants belonged to any particular...