Opinion ID: 1438901
Heading Depth: 1
Heading Rank: 5

Heading: dna typing procedures

Text: Before addressing the trial court's DNA evidentiary rulings, we state our understanding of the underlying concepts and principles generally employed by courts when confronted with DNA typing evidence. We recognize, as did the trial court, that this is an atypical case in that defendant chose not to present any DNA expert to contest or question the procedures and findings of the State's FBI experts. In nearly all the reported cases involving DNA evidentiary rulings, the trier of fact, and the appellate court, have been provided with the testimony of at least several expert witnesses, both in support of and opposition to the admission of the DNA evidence. See, e.g., State v. Cauthron, Wash. Supr. ( en banc ), 846 P.2d 502 (1993); State v. Vandebogart, 136 N.H. 365, 616 A.2d 483 (1992); United States v. Yee, N.D.Ohio, 134 F.R.D. 161 (1991); and Jakobetz, supra . Those cases were also decided several years after the instant case; and those trial courts, and appellate courts, have thus had the benefit of developing knowledge in this forensic science. DNA court decisions since 1992 have relied upon a report of the Committee on DNA Technology in Forensic Science, National Research Council, DNA Technology in Forensic Science (National Academy Press April 1992) (hereafter  DNA Committee Report ). See Cauthron, 846 P.2d at 508-10; Vandebogart, 136 N.H. 365, 616 A.2d at 485-88. With the approval of this Court, and principally for our assistance, the record on appeal was supplemented to include this report, to which counsel has made reference in the briefing of the appeal. DNA is an organic material found in chromosomes, which are contained in the nucleus of a cell. [8] Human genes are said to be carried in 23 pairs of chromosomes, with one chromosome in each pair being inherited from each parent. Molecules of DNA provide the molecular genetic code that determines the unique characteristics of any living organism. In humans, DNA can be located in white blood cells, sperm, hair roots and saliva. A fundamental premise of molecular theory is that all inheritable information is contained in a DNA molecule and that every DNA molecule within an individual is identical. The important feature of DNA for forensic science purposes is that, with the exception of identical twins, no two people have the same DNA makeup. Nevertheless, because human beings share more biological similarities than differences, most individuals share DNA molecules which are the same. There are, however, segments of DNA which are highly variable among individuals. The goal of DNA type testing is to detect these small differences among DNA samples taken from different individuals or sources. DNA typing involves three steps: a DNA sample is processed or typed (which the FBI refers to as its RFLP analysis); and a DNA print is produced from two samples  one from the bodily material discovered at the crime scene and the other taken from the suspect. The second step involves a comparison or matching of the genetic-marker types of the different samples to determine whether the samples could have originated from the same source. Assuming a match is found to exist between the samples, the third step consists of a statistical analysis of population frequencies to ascertain the statistical significance of the match, i.e., What is the probability that such a match would have occurred between a suspect and a person drawn at random from the same population as the suspect? See DNA Committee Report at 4.