U.S. v. Trala, CR. A. No. 00-23-GMS.

• Decision Date: 17 September 2001
• Docket Number: CR. A. No. 00-23-GMS.
• Citation: 162 F.Supp.2d 336
• Parties: UNITED STATES of America, Plaintiff, v. John Walter TRALA, and Melissa Bailey, Defendants.
• Court: U.S. District Court — District of Delaware

162 F.Supp.2d 336

UNITED STATES of America, Plaintiff, v. John Walter TRALA, and Melissa Bailey, Defendants.

CR. A. No. 00-23-GMS.

United States District Court, D. Delaware.

September 17, 2001.

COPYRIGHT MATERIAL OMITTED

Keith M. Rosen, Assistant U.S. Attorney, Wilmington, DE, Colm F. Connelly, U.S. Attorney, for Plaintiff.

Penny Marshall, Assistant Federal Public Defender, Wilmington, DE, for Defendants.

MEMORANDUM OPINION

SLEET, District Judge.

I. INTRODUCTION

On January 14, 2000, John Walter Trala ("Trala") was charged by indictment with robbery while armed, conspiracy, and using a firearm during a crime of violence in connection with the robbery of a bank in Bear, Delaware. At a location outside of the bank, a black ski mask and red jacket were collected by the FBI and sent to the FBI laboratories. A report dated August 15, 2000, indicated that a DNA sample taken from the ski mask matched a known DNA sample of Trala. The Government intends to use this evidence at trial.

On December 5, 2000, the defendant filed a motion in limine challenging the admissibility of the government's expected expert trial testimony on the results of the analysis of the DNA sample recovered from the scene of the alleged crime. This challenge is mounted pursuant to Rule 702 of the Federal Rules of Evidence. According to the defendant, the DNA evidence should be excluded because it fails to meet the standards for admissibility described in Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579, 113 S.Ct. 2786, 125 L.Ed.2d 469 (1993). The court conducted an evidentiary hearing on the issue from May 7, to May 10, 2001. Upon consideration of the evidence introduced at the Daubert hearing and the parties' arguments, the court finds that the expert testimony at issue is relevant, reliable, and would assist the jury in making related determinations. Thus, the court will deny the defendant's motion. The reasons for the court's decision are set forth in detail below.

II. BACKGROUND

A. Testifying Experts

At the evidentiary hearing, the court heard testimony from three expert witnesses for the government and one expert witness for the defendant. Dr. Bruce Budowle, Brendan Shea, and Dr. Ranajit Chakraborty were called by the government. Dr. William Shields was called by the defendant.

Dr. Budowle, the government's primary witness, is a Senior Scientist at the FBI Laboratory Division in Washington, D.C. Dr. Budowle testified about the basic concepts of DNA, different types of DNA typing, with specific emphasis on the typing and kits used in this case, and other issues concerning the reliability of the typing used in this case.

Brendan Shea is a Forensic Examiner employed by the FBI DNA Analysis Unit I. As a forensic examiner, Shea is responsible for supervising a team of biologists that performs the various stages of DNA amplification and analysis. Shea testified about the PCR-STR typing as it was conducted specifically in this case.

Dr. Chakraborty is the Allan King Professor of Biological Sciences, Population Genetics, and Biometry at the Human Genetics Center, University of Texas at Houston. Dr. Chakraborty testified about statistics, population genetics, and DNA analysis.

The defendant's witness, Dr. Shields, is a professor at the State University of New York, College of Environmental Science and Forestry. Dr. Shields testified about the reliability of PCR/STR typing as well the reliability of the statistical methods used.

B. Description of DNA Testing

1. Basic Concepts of DNA¹

Each human body contains a large number of cells, each of which descends from successive divisions of the fertilized egg that was its origin. Virtually all non-reproductive cells in the body contain identical copies of a complex structure called deoxyribonucleic acid or, DNA. This structure represents the genetic code for that individual. The DNA is in the form of microscopic chromosomes, which are located in the nucleus of a cell. A chromosome is a thread of DNA surrounded by other materials, mainly protein. A fertilized egg contains 23 chromosomes, with one member of each pair being contributed by the mother and father, respectively. Each cell contains identical, duplicates of the 46 cells from the fertilized parent cell. Therefore, each cell in the human body has the same DNA.

The structure of DNA consists of two strands, coiled in the form of a double helix (i.e., a twisted ladder). Each strand is composed of a string or a sequence of nucleotide bases held together by a sugar-phosphate backbone. To use the ladder metaphor, running between the sugar-phosphate strands (the side rails of the ladder) are billions of rungs, each of which is composed of two bases. There are only four possible types of bases — A, T, G, C. "A, T, G, C" represent adenine, thymine, guanine, and cytosine, respectively. The order in which the base pairs appear on the DNA ladder constitutes an individual's genetic code.

A gene is a particular DNA sequence located along a chromosome, ranging from a few thousand to tens of thousands of base pairs, that produces a specific product in the body. In other words, a gene is a site (a sequence of letters) on the DNA that encodes for a protein. A marker is a site on the DNA that does not code for proteins; the marker is also known as the locus (or location). Tr. at A34. In essence, the specific base sequence on the gene acts as an encoded message to the body to produce certain amino acids, which ultimately combine to form a protein. The function of a given gene is determined by the order of bases in the gene. The position that gene occupies along the DNA thread is known as its locus.

Human beings share more biological similarities than differences. Thus, over 99% of human DNA does not vary from person to person. Each person's DNA, however, has certain regions where the rungs of the ladder will be different. This area where a locus is different is polymorphic. The possible arrangements of base pairs that could occur in one of these polymorphic areas (i.e., the alternative forms of a gene that an individual could possess) are known as alleles. These alleles can result from differences in single base pairs, differences in multiple base pairs, or differences in the number of base pairs found in a given region. The individual genetic makeup described by the alleles is known as the genotype. In forensic analysis, the genotype for a group of analyzed loci is called the DNA profile. When a sample of DNA is typed, the lab examiner looks at predetermined polymorphic loci, identifies the alleles that make up the DNA sequence at those polymorphic loci, and then determines how likely it is for this sequence to appear in a given population.

2. Description of DNA testing

In this case, the laboratory used a method of DNA typing known as PCR/STR typing. In PCR/STR typing, a process known as polymerase chain reaction, or PCR, is used to amplify targeted loci of the sample of DNA by replicating the process by which DNA duplicates itself naturally. Thus, the lab is able to produce a substantial number of specific, targeted segments of DNA which can then be typed and compared. Short Tandem Repeats, or STRs, are a group of loci which are used to type and compare the DNA. Finally, statistics are used to evaluate how likely it is that a similar match would occur if the DNA sample were drawn randomly from the population. The court will briefly further describe the typing methods used below.

a. PCR Amplification Process²

PCR, a sample preparation technique, is a laboratory process for copying a short segment of DNA millions of times. The PCR process is analogous to the process by which cells replicate their DNA naturally. See United States v. Gaines, 979 F.Supp. at 1435. By using this process, a lab can produce a substantial number of specific, targeted segments of DNA which can then be typed and compared. PCR allows the laboratory to amplify only those specific DNA regions which exhibit genetic variations within the population, allowing for DNA typing. Moreover, the PCR process enables the analysis of very tiny amounts of DNA. PCR also permits the analysis of old and/or degraded DNA samples.

The PCR process is comprised of three steps. First, the double-stranded segment of DNA is separated, or denatured, into two strands by heating. This denatured DNA strand forms a template that can allow the manufacture of a new strand that is identical to its former complimentary strand.

Next, each of the single-strand segments are hybridized with primers. Primers are short DNA segments that are designed to bind with the template at particular loci. The primers are designed to compliment a sequence just outside of a target sequence of bases.

Finally, each primer serves as a starting point for the replication of the target sequence. In this third step, a type of enzyme called a polymerase becomes active. In essence, the polymerase facilitates repeated additions of bases to the primer until a new, complimentary strand of the targeted DNA locus is created.

This process is repeated a number of times, creating an exponentially increasing number of copies of the targeted area of the original DNA. Eventually, the PCR amplification process yields a sufficient quantity of the DNA sample to be typed. If the laboratory wants to type the DNA sample at multiple sites, it can add additional primers which will bind simultaneously to their respective target sites. This process is known as multiplexing. According to Dr. Budowle, multiplexing allows the laboratory to minimize the chance of human error and contamination in the PCR process. Using current technology, the FBI laboratory can multiplex up to fifteen or sixteen markers with reliable results.

b. Short Tandem Repeats³

The PCR process is performed to amplify a targeted locus (or loci) for analysis. These loci are selected because they are polymorphic, thus, making them amenable to typing. One group of such loci...