State v. Tankersley

• Citation: 956 P.2d 486,191 Ariz. 359
• Decision Date: 13 March 1998
• Docket Number: No. CR-94-0168-AP,CR-94-0168-AP
• Parties: , 264 Ariz. Adv. Rep. 41 STATE of Arizona, Appellee. v. Bobby Lee TANKERSLEY, Appellant.
• Court: Supreme Court of Arizona

Page 486

956 P.2d 486

191 Ariz. 359, 264 Ariz. Adv. Rep. 41

STATE of Arizona, Appellee. v. Bobby Lee TANKERSLEY, Appellant.

No. CR-94-0168-AP.

Supreme Court of Arizona En Banc.

March 13, 1998.

Grant Woods, Attorney General by Paul J. McMurdie, Chief Counsel, Criminal Appeals, Christopher E. Avery, Assistant Attorney General, Phoenix, for Appellee.

Richard D. Engler and M. Josephine Sotelo, Chief Deputy Yuma County Public Defender, Yuma, for Appellant.

OPINION

ZLAKET, Chief Justice.

¶1 On November 18, 1991, police discovered the body of 65-year-old Thelma Younkin in her room at Yuma's Post Park Motel. She had been strangled, most likely by means of the oxygen tube she regularly used to assist her breathing. There were bite marks on her breasts and face, her right earlobe had been bitten off, and a tooth was discovered beneath the body. The victim's vaginal area was extensively bruised and lacerated, and the medical examiner detected evidence of semen. Fecal matter was found on her legs, around the bathroom sink, and on a washcloth.

¶2 Defendant Bobby Lee Tankersley became a suspect early in the investigation. He lived at the same motel and was seen entering Thelma's room on the night of the murder. Police learned that the defendant had argued earlier that day with the victim's daughter, who warned him to leave her family alone. He allegedly replied, "I will get you before you get me." Immediately following discovery of the body, a police officer observed that the defendant was "rather buoyant and exhibiting laughter and exuberant behavior." He "was in a party mood" and "seemed to be nervous, pacing back and forth"--conduct that the officer considered "inappropriate for the circumstances."

¶3 DNA (deoxyribonucleic acid) analysis established that Tankersley could not be eliminated as the source of a hair recovered from fecal matter on the sink. Additionally, a forensic odontologist testified it was "highly probable" that defendant had bitten the victim's left breast, and another said that his teeth "matched" the bite marks. Saliva with H antigens, of which the defendant is a secretor, was found in the bite wounds.

¶4 Following a jury trial, Tankersley was convicted of first degree murder and sexual assault. The trial judge sentenced him to death for the homicide and to a consecutive aggravated term for the assault. Defendant appeals from both convictions and sentences. We have jurisdiction pursuant to Ariz. Const. art. VI, § 5(3); A.R.S. § 13-4031; Ariz. R.Crim. P. 26.15 and 31.2(b).

DNA EVIDENCE

¶5 Defendant challenges the admission of DNA evidence derived from polymerase chain reaction (PCR) testing. He does not attack the scientific theory of PCR, but rather its application to crime scene evidence. Defendant also asserts that the techniques and procedures used by the lab in this case are not generally accepted as capable of producing valid, reliable results. Finally, he questions whether the prosecution laid a proper foundation for the evidence.

¶6 PCR differs significantly from restriction fragment length polymorphis (RFLP), the technique approved in State v. Bible, 175 Ariz. 549, 577 & n. 17, 858 P.2d 1152, 1180 & n. 17 (1993), and used in State v. Boles, 188 Ariz. 129, 131-32, 933 P.2d 1197, 1199-1200 (1997); State v. Hummert, 188 Ariz. 119, 122-24, 933 P.2d 1187, 1190-92 (1997); and State v. Johnson, 186 Ariz. 329, 330, 922 P.2d 294, 295 (1996). Its admissibility is an issue of first impression for this court. A detailed description of the PCR technique can be found in George F. Sensabaugh & Cecilia von Beroldingen, The Polymerase Chain Reaction: Application to the Analysis of Biological Evidence, in Forensic DNA Technology 63-82 (Mark A. Farley & James J. Harrington eds.1991). See also Kary B. Mullis, The Unusual Origin of the Polymerase Chain Reaction, Sci. Am., Apr. 1990, at 56. We attempt only a brief overview here to provide a foundation for our legal analysis.

¶7 PCR is a process for reproducing a short segment of DNA millions of times, making it possible to analyze minute or degraded samples. National Research Council, The Evaluation of Forensic DNA Evidence 69-70 (1996) [hereinafter 1996 NRC Report ]. First, the extracted DNA is combined with a mixture of polymerase and "all of the building blocks necessary for DNA replication." Kamrin T. MacKnight, The Polymerase Chain Reaction (PCR): The Second Generation of DNA Analysis Methods Takes the Stand, 9 Santa Clara Computer & High Tech. L.J. 287, 305 (1993). The product is then heated in a "thermal cycler," which causes the double-stranded DNA to separate (denature) into two single strands (like splitting a ladder down the middle). Id.; see also Thomas M. Fleming, Annotation, Admissibility of DNA Identification Evidence, 84 A.L.R.4th 313, 319 (1991). When the solution cools, primers ¹ bind (anneal) to complementary base sequences ² on the single-stranded templates. Sensabaugh & Von Beroldingen, supra, at 64. Next, polymerase starts the synthesis of new DNA strands (extension) by assembling nucleotide ³ building blocks that are complementary to the template strands. MacKnight, supra, at 305. As a result, two double-stranded segments of DNA, identical to the original, are created. The process is repeated, and with each new cycle, the DNA doubles in size. Sensabaugh & Von Beroldingen, supra, at 64. Once a sufficient amount of the targeted DNA has been produced, a profile or typing can be done. Id. at 66.

¶8 PCR is only an amplification process and does not directly analyze DNA. To do that, a genetic marker typing test must be used. Id. The test employed in the present case was the AmpliType DQ-alpha kit by Cetus Corporation. This kit, in analyzing the DQ-alpha gene, had the capability of detecting six alleles, termed 1.1, 1.2, 1.3, 2, 3, and 4. P. Sean Walsh et al., Report of the Blind Trial of the Cetus AmpliType HLA Dq Forensic Deoxyribonucleic Acid (DNA) Amplification and Typing Kit, 36 J. Forensic Sci. 1551, 1552 (1991). Each individual has two alleles that are either the same (e.g., 1.2, 1.2) or different (e.g., 1.2, 4). See People v. Lee, 212 Mich.App. 228, 537 N.W.2d 233, 250 (1995), appeal denied, 453 Mich. 884, 554 N.W.2d 12 (1996).

¶9 To identify a specimen's DQ-alpha profile, short DNA segments that detect specific alleles, called "probes," are fixed to a nylon membrane at a particular location. 1996 NRC Report, supra, at 71-72; see also Scientific Evidence, supra, at 327 (for definition of probe). The amplified DNA is again denatured and then flooded over the membrane. A chemical reaction occurs wherever the sample DNA finds its complementary probe, causing a blue dot to appear at that location. The positions of the dots indicate the specimen's DQ-alpha genotype. MacKnight, supra, at 306-07. This procedure is known as "reverse dot blotting." National Research Council, DNA Technology and Forensic Science 42 (1992) [hereinafter 1992 NRC Report ].

¶10 Once this genotype is determined, it is compared to the DNA profile of the crime suspect. If the two are different, the person is excluded. If they "match," then the suspect is a possible source of the specimen, and questions arise regarding frequency of the genotype in the population.

¶11 In this case, hairs found on the bathroom sink and on a washcloth, as well as blood samples from the defendant and the victim, were sent to Forensic Science Associates (FSA) for PCR DQ-alpha testing. Of the hair samples, only a single strand had sufficient root material from which DNA could be extracted. Testing revealed that defendant's genotype was 1.1, 2, while the victim's was 2, 4. The lab then determined that the hair's profile was 1.1, 2, thus eliminating the victim as a source but not excluding the defendant. Dr. Edward Blake, who owns and operates FSA, testified that 1.1, 2 occurs in about four percent of the Caucasian population.

¶12 Before trial, the court conducted an extensive Frye hearing, admitting more than eighty publications on PCR technology. The state called two witnesses: Dr. Blake and Dr. Helentjaris, a plant DNA expert at the University of Arizona. Three defense experts, Drs. Grunbaum, Gerdes, and Riley, testified about PCR analysis, FSA's laboratory procedures, and the testing done in this case. At the close of the hearing, the court found that the DNA evidence was admissible, stating that the defense's real complaint was of "dirty test tubes," not reliability of the methodology. In the trial court's view, any problem with FSA's procedures could be explained to the jury, which would then assess its impact.

Standard for Admissibility of New Scientific Evidence

¶13 Although not raised below, the state asks this court to abandon the Frye test in favor of the current federal standard for determining the admissibility of new scientific evidence. See Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579, 589, 113 S. Ct. 2786, 2793, 125 L.Ed.2d 469 (1993) (holding that Frye v. United States, 293 F. 1013 (D.C.Cir.1923), was superseded by the Federal Rules of Evidence). We decline to do so. In Johnson, 186 Ariz. at 331, 922 P.2d at 296, we reaffirmed our adherence to Frye. See also Bible, 175 Ariz. at 578-80, 858 P.2d at 1181-83. Moreover, in light of the prosecution's failure below to request application of the Daubert decision, the issue is not properly before us.

¶14 The state also argues that if Frye is preserved, it should govern only general principles such as "the variability of human DNA and its replication via a polymerase chain reaction," not the forensic application of PCR or specific techniques used in implementing this technology. We disagree. The following excerpt from the National Research Council's 1992 report is instructive:

"DNA typing" is a catch-all term for a wide range of methods for studying genetic variations. Each method has its own advantages and limitations, and each is at a different state of technical development. Each DNA typing method...