Opinion ID: 2036519
Heading Depth: 1
Heading Rank: 18

Heading: Human Hairs Recovered From the Body

Text: Richard Caudell, the crime-scene technician, observed hairs stuck in the rectum area of the victim. Dr. Nuernberger, who performed the autopsy, also observed hairs adherent to the anal crease and the buttocks    by fecal matter. Kenneth Knight, a forensic scientist and expert in hair and fiber analysis, examined the hairs recovered from the victim's rectum: eight Caucasian head hairs, which were consistent with Amy's head hairs; two Caucasian pubic hairs, which had been forcefully removed from the source; one Caucasian hair of undetermined body origin; and one animal hair, whose species could not be identified. The pubic hairs were used to screen suspects because of their location on the victim and the fact that the victim was prepubertal and thus had no pubic hair of her own. In July 1987, Knight conducted microscopic comparisons of the two pubic hairs found on the victim with pubic hair standards from Dennis, Esther, Adam and Ryan Schulz, Gwen and William Willis, and 23 other individuals. In making his comparisons, Knight considered 23 characteristics, including the hair's relative length and color; the hair's configuration, i.e., whether the hair was straight, curly, or wavy; whether the tip of the hair was tapered, broken, rounded, cut or shaved; whether the root was retched, putrid, or bulbous; the size of the shaft; whether the base of the hair was pigmented or damaged; the scale pattern; and the cuticle. Knight explained that to make a determination that an unknown hair could have originated from the same source as a known standard, all the characteristics present in the unknown hair must be present in the standard, with no unexplained differences. When a difference exists that cannot be explained, the source of the known standard must be excluded as a source of the unknown hairs. Based on his microscopic analysis, Knight concluded that the pubic hairs recovered from the victim were dissimilar to the pubic hairs standards from the Schulzes, Willises, and the 23 other individuals and did not originate from them. Knight also microscopically compared the two pubic hairs with pubic hair standards from defendant and determined that the hairs were consistent with each other. Knight noted a difference in pigmentation in the shaft of defendant's hair, but considered this difference insignificant. Knight concluded that the pubic hairs found on the victim could have originated from defendant. According to Knight, five other examiners reviewed his work with regard to defendant's hair standards, and all five examiners agreed with his conclusion. The pubic hairs recovered from the victim and the standards obtained from defendant were also subjected to mtDNA analysis. Harold Deadman, the State's expert on forensic analysis of hair, fiber, and DNA, testified that human hair comparisons based on microscopy are quite difficult because microscopy involves a subjective examination, and the ability to get the right answer depends on the skill of the person doing the comparison. Deadman further testified that mtDNA analysis is a more objective technique and, when performed after microscopy, functions as kind of a quality control mechanism, likely to pick up a mistake by the microscopist. Neither method, however, provides absolute identification. The differences between nuclear DNA and mtDNA were explained by Harold Deadman, as well as John Planz, an expert in the application of DNA and mtDNA techniques in forensic testing, and Terry Melton, whose lab, Mitotyping Technologies, performed the mtDNA analysis in this case. Generally, nuclear DNA is found in the nucleus of a cell and is transmitted by both parents to their offspring. In contrast, mtDNA is housed in the mitochondria of a cell, found in the cytoplasm surrounding the nucleus. No paternal contribution is made to mtDNA; it is inherited only maternally. Thus, a mother, her children, the mother's siblings, and the mother's maternal ancestors all have the same mtDNA. A nuclear DNA molecule has a double helix structure and contains three billion base pairs consisting of four chemicals: adenine, thymine, cytosine and guanine. Although mtDNA also exhibits a double helical form, it is more compact and contains only about 16,569 base pairs. Scientists conducting DNA analysis of two samples compare the sequencing of the base pairs in certain control regions on the DNA strands. A match between two nuclear DNA profiles is much more discriminating than a match between two mtDNA profiles. Terry Melton testified that her laboratory performed an mtDNA analysis of the two pubic hairs found on the body, and blood samples obtained from defendant and William Willis, Amy's step-grandfather. Melton explained that the mtDNA is first extracted, then copied and sequenced, producing a string of chemical bases 783 long. The sequences from the known sample and unknown sample are then compared. A single difference is inconclusive. Two or more differences means that the donor of the known sample, along with the donor's maternal relatives, are all excluded as the source of the unknown sample. A complete match between the two sequences means that the known individual, and his or her maternal relatives, cannot be excluded as the donor of the unknown sample. If a match is obtained, a search of the Scientific Working Group on DNA Analysis Methods (SWGDAM) database reveals how rare or common the sequence may be in the general population, allowing for further statistical analysis. John Planz explained that the SWGDAM database, which the Federal Bureau of Investigation (FBI) maintains and controls, contains over 4,000 mtDNA sequences from primarily North American populations and is constantly growing. The mtDNA sequencing performed at Melton's laboratory disclosed numerous differences between the mtDNA sequences in the two pubic hairs found on the victim and in Willis' blood. Thus, Willis was excluded as a possible donor of the two pubic hairs. However, a comparison of the mtDNA sequences from the unknown hairs and defendant's blood produced a match. Melton's laboratory analyzed a third hair of unknown origin removed from the sheet used in transporting the body to the morgue. The mtDNA analysis excluded Willis, the victim, and defendant as the source of the hair. Melton did not find the absence of a match significant. She testified that because humans shed between 75 and 100 hairs per day, it is not uncommon to find hairs at a crime scene that are unrelated to the crime. Melton's laboratory analyzed a fourth hair, identified as a human hair from the victim's rectal crease. The mtDNA sequence in this hair was identical to the mtDNA sequences in the two pubic hairs recovered from the body, as well as the mtDNA sequence obtained from defendant's blood. To determine the significance of the match between the mtDNA from the three hairs found on the victim and the mtDNA in defendant's blood, a search was made of the SWGDAM database. Melton testified that this type of sequence had never been observed in the database, indicating a certain rarity in the population. Statistically, the sequence observed here would not be expected to occur in more than six one-hundredths of one percent (.06%) of the North American population. Stated differently, at least 99.94% of the North American population would not be expected to have this type of mtDNA sequence. Melton further explained: So the vast majority of people will not have this type, and we place that with what we call a 95 percent confidence. So five percent of the time it could be different, but it's not likely to be more than that 95 percent of the time. Melton also clarified that we cannot ever eliminate the possibility that a maternal relative [of defendant] was the donor of the hairs found on the victim. Testimony from various family members established that defendant had numerous maternal relatives, and that defendant, Michael Sutherland, Kenneth Sutherland, and their uncle Walter Sinclair, all lived within eight or nine minutes of each other. Melton further testified that no measurable pooling of genes exists in any of the regions of the United States that have been sampled, and she has not seen mtDNA sequences that appear to be abundant in one region that are not abundant somewhere else. [W]e don't have any indication that we would go out into a particular city or town and start seeing one type picked at random over and over again. Not if we have a population to choose from of some size. William Shields, a defense expert in population and molecular genetics, reviewed Melton's mtDNA reports. Shields testified that Melton's reputation in the scientific community was very good and that the laboratory results Melton obtained were good clean results. Shields disagreed, however, with Melton's statistical analysis and her use of the SWGDAM database. In his opinion, Melton underestimated the frequency of the mtDNA sequence in this case, thus overstating the significance of the match. Shield's disagreement stemmed from the notion of population substructure, the fact that the frequency of genetic types will differ among groups of different kinds. To illustrate his point, he offered the following example: Red heads have a reasonably low frequency. If you look at the whole world's population. And, in fact, if I was in    what used to be called the Belgium [ sic ] Congo, and somebody told me a red head committed a crime, I could probably find that there were only three or four red heads in the population   , which would give me a pretty good handle on what was going on. The frequency would be very low   . But if I went to an Irish village in a particular place in Ireland, where 90 percent of the people are red heads, it would have very little meaning. That's the difficulty. Shields noted that in this case, there are at least three individuals besides defendant who share the same mtDNA, but that this information is not reflected in the SWGDAM database used by Melton. He testified that a way to insure that the worth of the evidence is not overestimated is to develop an upper limit, i.e., a frequency that the true frequency is not likely to be greater than. Shields testified that because the population in the geographic area of the crime is not known, the best estimate of the likelihood that someone drawn at random from that population would be a match with the mtDNA from the crime scene is the largest number seen in any populations that are known. The largest such number seen in any population reflected in the SWGDAM database is 1 in 12, reflected in the Thai population. What it means is we think that if the Thais could have this level of matching, so could a local population that we've not sampled. Robert Makuch, a defense expert in biostatistics, agreed with Melton's calculations, but disagreed with her conclusion that we can exclude 99.93% of the population as contributors of the questioned sample. Melton's report, which Makuch reviewed, stated that, based on a database of 4,142 mtDNA sequences, the 95% confidence limit is 0.000722, or .07%, meaning that there is a 5% chance that the true frequency in the population exceeds 0.07%. Makuch explained that, multiplying 4,142 by .07 yields a value of 3. So what it really is saying within 95 percent confidence,    it would be reasonable for us to see between zero matches and up to three matches with a data base of this size.    [B]ut then to turn it on its head and then to say that we can exclude 99.93 percent of the population is in biostatistics, it's simply an inappropriate conclusion for those kinds of data. Makuch also testified that from a practical standpoint, we know that defendant's siblings have the same mtDNA. In rebuttal, the State called Bruce Budowle, a senior scientist with the FBI who had a primary role in developing the SWGDAM database. Budowle did not disagree with either Melton's calculations or Makuch's calculations, testifying that the results each obtained are simply expressed differently. Budowle did, however, disagree with Shields' worst-case scenario that the mtDNA frequency in this case is one in 12. Budowle also testified that even in small communities, the pooling of a particular mtDNA sequence does not occur to the degree necessary to affect case interpretation. Additionally, Harold Deadman testified that knowing defendant has brothers would affect only the associative value of the mtDNA evidence, but not the value of the microscopic hair comparisons. Deadman testified that even the hair from identical twins could be microscopically dissimilar. Thus, although Deadman had not seen any reports concerning microscopic examinations of the hair of defendant's siblings and other maternal relatives, he would not expect their hair to be microscopically similar to defendant's hair.