The entire basis of this thread is to counter the outrageous claim that the type of *autosomal* DNA which is loaded to gedmatch could *EVER* result in a false positive. It can *never* result in a false positive.  Autosomal DNA is so precise it can tell parent from child, sibling from sibling, cousin from cousin.  There is no such thing as a false positive. -----Original Message----- From: Dave Hamm via GENEALOGY-DNA <genealogy-dna@rootsweb.com> To: genealogy-dna <genealogy-dna@rootsweb.com> Cc: Dave Hamm <odoniv@yahoo.com> Sent: Tue, Nov 27, 2018 6:14 am Subject: [DNA] Re: Use of familial search by law enforcement WJohnson, Easy for you to say, without citing any sources. One of the examples I gave was regarding the CODIS markers, which is the DNA used for conviction in court. That happens regardless of the type of DNA samples have been examined. The CODIS markers convicted Chen, and the jury ignored the remaining evidence. "Five years later, Chen was exonerated when a second DNA test that found he was not a match after all. In the years he lived as a convicted rapist, he had lost his wife, his business and most of his life." Gizmodo: "When Bad DNA Tests Lead to False Convictions" https://gizmodo.com/when-bad-dna-tests-lead-to-false-convictions-1797915655 His original 17 genetic markers were overturned when testing more markers showed that he was not a match. This was not sloppy police work, this was the presumption that DNA analysis is accurate to within millions of suspects. This was at a time when 13 CODIS markers were believed to be accurate to one in millions. In Chen's case, CODIS was not accurate to within one bar that night. A cynic could presume that means nearly doubling the number of markers to 20 CODIS markers would not be not accurate to the people within two night clubs. see: "Average Probability that a “Cold Hit” in a DNA Database Search Results in an Erroneous Attribution (2009)" "Random match probability (RMP), defined to be the probability that a person picked at random has the same DNA profile as the evidentiary sample, is very low if several unlinked loci are typed. For a 13-locus CODIS profile, typical RMPs are on the order of 10^−14 to 10^−15.... Such a low RMP implies that a particular DNA profile has a high probability of being unique. To compute the RMP, the recommendation of the second National Research Council Report (NRC II) is usually followed." That article mentions that for a population of 300 million, "we obtain the probability of an erroneous attribution of approximately 2.93 × 10−7 or approximately 1 in 3.4 million." I have seen similar claims from genetic genealogists regarding 20 CODIS markers. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5124364/ Now, New York has recently reviewed some 800 case files, where the CODIS DNA markers were not properly handled. There were some cases of "sorry we convicted you and you spent time in jail, but we messed up your DNA sample." see:  "New York Examines Over 800 Rape Cases for Possible Mishandling of Evidence" "The New York City medical examiner’s office is undertaking an unusual review of more than 800 rape cases in which critical DNA evidence may have been mishandled or overlooked by a lab technician, resulting in incorrect reports being given to criminal investigators. Supervisors have so far found 26 cases in which the technician failed to detect biological evidence when some actually existed, according to the medical examiner’s office. In seven of those cases, full DNA profiles were developed — in some instances, evidence that sex-crime investigators did not see for years, hampering their ability to develop cases against rape suspects. In one of those instances, the newly discovered DNA profile matched a convicted offender’s sample, leading to an indictment a decade after the evidence was collected, according to Dr. Mechthild Prinz, the director of forensic biology at the medical examiner’s office. In two other instances, the new DNA profiles were linked to people either already convicted or under suspicion. The scope of the problem has yet to be determined; at several points over nearly two years, supervisors in the medical examiner’s office thought they had gotten to the bottom of the technician’s errors, only to find that the trail went further." https://www.nytimes.com/2013/01/11/nyregion/new-york-reviewing-over-800-rape-cases-for-possible-mishandling-of-dna-evidence.html?module=inline I have not reviewed these cases in order to determine how many used what type of DNA to investigate the crimes.  - Dave Hamm RE: On 11/26/2018 3:31 PM, genealogy-dna-request@rootsweb.com wrote: > Date: Mon, 26 Nov 2018 18:40:41 +0000 (UTC) > From: Wjhonson <wjhonson@aol.com> > Subject: [DNA] Re: Use of familial search by law enforcement > To: genealogy-dna@rootsweb.com > Cc: odoniv@yahoo.com > Message-ID: <535140636.2840620.1543257642102@mail.yahoo.com> > Content-Type: text/plain; charset=UTF-8 > >  The Y test you cited is not good evidence of anythingTHOUSANDS of men have the exact same Y results on 12 and even on 37Using a Y test for a crime scene is just utter stupidity on the part of the police > The other example isn't actually an example of anything DNA relatedThe test in question was the father's, the subpoena was merely because he was a *close* matchAnd the *actual* test showed that he was not a match > So once again, my claim, that no Autosomal DNA test has *ever* found a positive match, that was later overturned > By the way, that you might be *present* at an event where a crime *later* took place is just sloppy police workNot evidence of an overturned DNA test Wjhonson, RE: > "It is completely untrue that “improvements” in dna have exonerated anyone... _______________________________________________ Email preferences: http://bit.ly/rootswebpref Unsubscribe https://lists.rootsweb.com/postorius/lists/genealogy-dna@rootsweb.com Privacy Statement: https://ancstry.me/2JWBOdY Terms and Conditions: https://ancstry.me/2HDBym9 Rootsweb Blog: http://rootsweb.blog RootsWeb is funded and supported by Ancestry.com and our loyal RootsWeb community

Autosomal DNA tests, of the 700,000 marker sort used by the commerical companies, can never result in a false positive ***IF*** 1) no identical twin exists (there are tests that can tell them apart) 2) both samples are uncontaminated But for criminal purposes the 2nd is very very frequently not true. If a sample is contaminated, the chip tests can be useless. A high coverage (100x) Illumina full sequence of both samples would be better. Better yet would be a 100x long read (10xgenomics or the lastest claimed 99% accurate PacBio) full sequence, of the possibly contaminated sample. CODIS tests are just not extensive enough to be reliable for contaminated samples. If the CODIS (STR) idea had say 200 markers instead of the CODIS number (12???) then it would be better. Without that, I as a juror would be very leery unless there was clearly no possibility of contamination. Doug McDonald ________________________________ From: Wjhonson via GENEALOGY-DNA <genealogy-dna@rootsweb.com> Subject: [DNA] Re: Use of familial search by law enforcement The entire basis of this thread is to counter the outrageous claim that the type of *autosomal* DNA which is loaded to gedmatch could *EVER* result in a false positive. It can *never* result in a false positive. Autosomal DNA is so precise it can tell parent from child, sibling from sibling, cousin from cousin. There is no such thing as a false positive.