9 The Leskie Decision“ The match to the bib occurred as a result of contamination in the laboratory and was not an adventitious match. . ."
10 The Leskie Decision“ The samples from the two cases were examined by the same scientist within a close time frame."
11 Mixture Interpretation How does one interpret a mixture, that is, which bands or peaks are alleles and which are artifacts or errors?
12 Sample Mixture Example Profiler Plus data 4 peaks at a single locusD5S818D13S317D7S820D8S1179D21S11D18S51AmelVWAFGAD3S1358blue panelgreen panelyellow panelRelative Fluorescence UnitsHigher than expected stutterImbalance in X and Y peak ratios“Stutter” on wrong side of allele
24 60 profiles so far. We have 14 loci to go. . . 10 profiles from vWA6 profiles from D360 profiles so far. We have 14 loci to go. . .
25 Why this is hard: You don’t know how many people are in the mix You don’t know when and where their alleles overlapYou don’t know if you have alleles that have dropped out due to low copy numbersYou don’t know if you have a triallelic pattern or stutter or primer binding site mutation
52 Behavior patterns of degraded DNA To paraphrase Joe Walcott, “the bigger they are, the faster they fall.”Welterweight champion of the world, 1901 – 1904.
53 Behavior patterns of degraded DNA AmpFlSTR® Identifiler™ (Applied Biosystems)
54 Behavior patterns of degraded DNA AmpFlSTR® Identifiler™ (Applied Biosystems)AmpFlSTR® Identifiler™ (Applied Biosystems)
55 Behavior patterns of degraded DNA AmpFlSTR® Identifiler™ (Applied Biosystems)AmpFlSTR® Identifiler™ (Applied Biosystems)
56 What does this have to do with a ‘ski slope?’ AmpFlSTR® Identifiler™ (Applied Biosystems)D8S1179D21S11D7S820CSF1POThe smaller stuff is over hereTH01D13S317D3S1358D16S539D2S1338D19S433VWATPOXD18S51The Bigger stuff is over here!!D5S818AMELFGASlide courtesy of John Butler
62 Heterozygous peak height balance as a function of signal intensity in RFU units.PHB50-150>1000 rfu’sObserved minimum48%57%58%78%Theoretical minimumMean -3 SDmean40%80%54%85%63%88%75%92%N145140233209Data from Holt, et al., J. Forensic Sci. 2002; 47(1):66-96.
95 Defendant12, , , 25Is he excluded?--No, because stochastic effect or preferential amplification explains peak height disparity at D3; spike (pull-up) at FGA hides 20 allele.
96 Special Thanks Bob Blaiser, Attorney John Butler, National Institute of Science and TechnologySimon Ford, Lexigen, Inc.Jennifer Friedman, LA Public Defender’s OfficeJason Gilder, Forensic Bioinformatics ServicesTed Kessis, Applied DNA ResourcesDave Knudsen, Minnesota State Public Defender’s OfficeDan Krane, Forensic BioinformaticsCarll Ladd, Connecticut State Crime LabCarrie Roland, Forensic Bioinformatics ServicesMike Sganga, Senior Scientist, Attorney, Law Office of Michael BurtBill Thompson, UC Irvine