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State v. Traylor

February 24, 2003



1. District court correctly concluded that PCR-STR DNA testing is generally accepted in the relevant scientific community as required under the first prong of the Frye-Mack test.

2. District court did not abuse its discretion in concluding that the appropriate standards and controls currently in effect are the DAB standards and that the BCA complied with those standards.

3. Primer sequences and unlimited access to validation studies are not necessary for the scientific community to validate multiplex DNA kits and therefore defendant's due process right to a fair trial was not violated.


Heard, considered, and decided by the court en banc.

The opinion of the court was delivered by: Blatz, Chief Justice


Appellant Raymond Joseph Traylor was convicted of second-degree assault and controlled substance possession in the fifth degree, in violation of Minn. Stat. §§ 609.222 and 152.025, subd. 2(1) (2002). In this appeal, Traylor contends that the district court erred in admitting deoxyribonucleic acid (DNA) evidence obtained by the Minnesota Bureau of Criminal Apprehension (BCA) via a new testing methodology. Traylor asserts that the BCA's current form of DNA testing does not meet this court's requirements for admissibility and reliability of evidence. At trial, the DNA evidence was admitted over Traylor's motion for suppression. Holding that the district court erred in its application of standards governing the admissibility of DNA evidence but that such error was harmless, the court of appeals affirmed Traylor's conviction. We reverse the court of appeals decision insofar as it held that the district court erred and affirm the conviction.

On November 13, 1999, Debra Clemons contacted the Minneapolis police and reported that she had been stabbed by Traylor, and that he was now asleep in her home. When police arrived, they found Traylor and arrested him. A small amount of cocaine was found on Traylor's person, and a bloody knife was found at the scene. The Minnesota Bureau of Criminal Apprehension subsequently performed DNA testing on the knife. Traylor challenged the district court's admission of the DNA evidence, asserting that the BCA's current method of DNA testing is a new, disputed technology. The district court held a Frye-Mack hearing, incorporating testimony from an earlier Frye-Mack hearing on the matter. The district court found the DNA evidence admissible, and ruled that the DNA Advisory Board (DAB) standards were the appropriate standards to govern the BCA's use of the new DNA testing methodology. The court of appeals held that the quality assurance standards relied upon by the district court were not the standards previously adopted by this court and therefore the admission of the DNA evidence was error. See State v. Traylor, 641 N.W.2d 335, 340-41 (Minn. App. 2002). However, the court of appeals affirmed Traylor's conviction and held that the error was harmless. Id. at 342. Both Traylor and the state cross-appealed to this court. The state contends that DNA testing as currently conducted by the BCA meets the Frye-Mack standard for the admissibility of scientific evidence and the court of appeals' reasoning in excluding the evidence was in error. Traylor, in turn, challenges the court of appeals decision that the error was harmless.

While the underlying science of DNA identification technology is not at issue here, a review of our prior case law as well as a brief discussion of the underlying science will be helpful in addressing the issues presented in this appeal. In State v. Schwartz, 447 N.W.2d 422, 425 (Minn. 1989), we explained the basic science of how DNA may be used for identification purposes:

DNA (deoxyribonucleic acid) is an extremely long, thread-like chain of molecules found in the nucleus of every cell in the body * * *. The DNA chains are tightly coiled up into bodies called "chromosomes," of which humans have twenty-three * * *. No two individuals, except for identical twins, have identical DNA. Within a given person, however, DNA does not vary from cell to cell. Id. (quoting William C. Thompson & Simon Ford, DNA Typing: Acceptance and Weight of the New Genetic Identification Tests, 75 Va. L. Rev. 45, 61 (1989)).

Early forensic DNA testing was performed using a method called Restricted Fragment Length Polymorphism testing (RFLP). This method has been accepted as reliable and accurate by this court. See State v. Roman Nose, 649 N.W.2d 815, 820 (Minn. 2002); State v. Jobe, 486 N.W.2d 407, 419-20 (Minn. 1992).

RFLP testing, however, is not without some limitations. Several witnesses at the Frye-Mack hearing below testified as to its disadvantages. Patricia Wojtowicz, supervisor of the biology section at the BCA, explained that because RFLP requires relatively large samples in order to work, it was unusable in situations where a smaller amount of bodily fluid was available. Ann Gross, a forensic scientist at the BCA who has performed many RFLP tests, noted that RFLP technology is not effective when working with degraded*fn1 DNA samples. Finally, Wojtowicz indicated that because the RFLP alleles, the alternative form of the genes being examined, could not be sized exactly, the use of "bins" was required. "Binning," the grouping of different sized alleles, is problematic because it decreases the accuracy of testing.

Since our decisions in Schwartz and Jobe, the FBI, in conjunction with state and local forensic laboratories, has created a computerized database of DNA profiles of known, convicted offenders and unknown forensic DNA samples. The Combined DNA Index System database, known as CODIS, allows law enforcement at all levels to compare DNA profiles electronically. CODIS initially used the RFLP methodology, but the disadvantages of that methodology proved limiting. Wojtowicz explained that the limitations led scientists to the "logical step" of development of new methods of DNA analysis that would avoid the pitfalls of RFLP. Two DNA-related options—Polymerase Chain Reaction and Short Tandem Repeats—were explored. Dr. Bruce Budowle, a senior scientist at the FBI and, at the time of the Frye-Mack hearing, the chair of the Scientific Working Group on DNA Analysis Methods, explained that PCR was explored because it was both "more sensitive" and allowed for a more easily automated procedure.

Polymerase Chain Reaction (PCR) is a method for replicating, also known as amplifying a portion of an individual's DNA. It essentially copies DNA, thus increasing the amount available to be tested. This method does not replicate the entire DNA strand. Instead, it generates millions of copies of a particular portion of DNA by repeatedly replicating a small, defined portion of the strand.

This replication is accomplished through the use of primers—small pieces of DNA that attach to a denatured single-stranded DNA and bracket specific genes in the DNA strand. The method is considered especially beneficial for forensic testing, as the replication allows for testing of both degraded DNA and small amounts of DNA. The BCA has used a type of PCR-based analysis since 1994.

To test only a portion of the DNA strand, as both PCR and RFLP methodologies do, the testing must focus on DNA that is unique to every individual. Dr. Budowle explained that while all humans share essentially the same genes, these genes are polymorphic, meaning they exist in different forms. It is the length of these polymorphic forms of genes that vary in size from person to person. Thus, determining the variation in length across a number of genes allows scientists to identify a person based on their DNA.

Recently, PCR testing began to examine a portion of human DNA known as short tandem repeats, or STRs. Both Dr. Budowle and Gross explained that every human has certain STRs, DNA in which a DNA sequence is repeated along the strand. However, because there is variation in the length of the STRs for each individual, examining a number of the STRs allows for identification. STRs are similar to the portion of DNA examined in RFLP testing, but the base pairs that are repeated are much smaller.

PCR-STR testing, or the testing of short tandem repeats via amplification of discrete portions of the DNA strand, came to prominence under the auspices of the FBI's STR Standardization Project. Wojtowicz explained that this project was a national effort of forensic DNA laboratories to determine which STRs would be best suited for forensic DNA testing. Dr. P. Michael Conneally, Distinguished Professor of Medical Genetics at the Indiana University Medical Center and a member of the Human Genome Organization, further testified that the twelve STR markers eventually settled upon, and used by CODIS, the BCA, and the FBI, have been accepted by the Human Genome Organization. The Human Genome Organization, or HUGO, is a coordinated national effort to map all human genetic material by determining the complete sequence of the human DNA.

To perform PCR-STR amplification and analysis of DNA is a five-part procedure:

Extraction—the DNA is isolated from bodily fluids.

Quantitation—the amount of the isolated DNA is determined.

Amplification—portions of the DNA strand are copied repeatedly to produce sufficient material for testing, either by DNA sequence variation or DNA fragment length variation.

Electrophoresis—amplified pieces of DNA are separated based on size, along with an allelic ladder, which contains fragments of a known size for each loci examined, for comparison.

STR determination—the size of the DNA fragments are determined by comparing the stratified ...

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