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Old 18th January 2020, 12:18 PM   #81
Chris_Halkides
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more on John Puckett

Originally Posted by ArchSas View Post
It seems like a lot of people here have an inherently positive view of law enforcement, and view it as a just institution that they can trust. That's not my default view.
Speaking for myself, I have seen too many instances in which there was poor quality work/thinking or occasionally outright malfeasance (Russ Faria case, for example) to be automatically certain that the police are correct. IMO several other people in this thread fall into the same category, and that when new facts become available, we change our minds.

Because I brought it up, I feel obliged to mention that the book Math on Trial (Leila Schneps) dealt with the John Puckett case. There was a series of articles on this case in the Los Angeles Times and the story was picked up elsewhere.

"In Sylvester’s case, the DNA was so degraded that the crime lab was only able to identify five and half markers; California requires a minimum of seven to even run a profile against its felony database. This meant the lab had to rely on inconclusive readings for two markers—one was so inscrutable, in fact, that there were three possible interpretations, each of which presumably could have led to a different suspect."

Although it is not specifically about familial searching, the Puckett case is relevant to the present discussion because it deals with partial profiles and database searches. There is also a chapter in Erin Murphy's book (mentioned upthread) which is worth consulting with respect to familial issues.
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Old 18th January 2020, 01:58 PM   #82
Elaedith
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Originally Posted by Chris_Halkides View Post
What book did you read? DNA from a single source is fine, but mixed DNA sampled, which are often recovered in forensic cases, have been analyzed subjectively in the past. See this link for a recent exoneration and discussion of mixed DNA analysis in light of PCAST. "In 2016, a presidential commission on forensic science citing Dror and Hampikianís study found that human interpretation of DNA mixtures in crime laboratories was 'problematic' because of subjective bias, and it concluded that 'subjective analysis of complex DNA mixtures has not been established to be foundationally valid and is not a reliable method.'" The issue of whether or not mixed profiles that are analyzed via computer software are also subjective is a difficult one.
Iím revising a lecture on cognitive biases in interpreting forensic evidence (for next week Ė Iíve ended up doing it a bit later than intended as usual) and Iíve been looking at some articles and videos by Prof. Dan Krane on observer effects in interpreting DNA profiles with ambiguous features. He was discussing the biasing effects of having the suspectís reference profile available when analyzing the evidence sample and the use of sequential unmasking as a remedy. In one of the talks (I think it was his TED talk, which I thought might be useful as a simple introduction for students) he implied that some labs were resisting the use of blinding procedures. These materials are a few years old now and I was wondering if this is still the case? Iíve found a few articles discussing the issue of blinding, but not much on whether labs are implementing better practices. Iím not sure how much transparency there is regarding labs reporting their procedures.

I realize problems with subjectivity involve DNA practices in general, but as the issue of validity is being put forward in relation to familial searches I thought itís somewhat relevant.

I had a chance to look at the book by Prof. Erin Murphy you pointed out before, and I noticed mention that some offenders caught by familial searches should have already been on an offender database due to previous convictions, but weren't due to labs being swamped with backlogs of samples. It made me wonder if expansion of the use of DNA profiling is outpacing the ability of labs to deal with it (both in terms of capacity and the need to ensure valid procedures).
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Old 18th January 2020, 02:39 PM   #83
Elaedith
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Originally Posted by Rolfe View Post
If a police investigation isn't allowed to breach the privacy of citizens, it's not going to get very far in most cases.

Consider internet browsing history. People generally regard that as private. Should the police not be allowed to access this?
I would expect/hope that some kind of authorization is required to access that, rather than police having free and unrestricted access whenever they want. It is a question of balancing the justification, grounds for suspicion and likelihood of finding important evidence against the right to privacy.
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Old 19th January 2020, 09:51 AM   #84
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I'm not sure about that, it may depend on the jurisdiction. I think they can insist on taking your computer and then if you won't give them the passwords that's when they have to get a court order.

I do think there's a sound argument for having to get a court order before being permitted to go trawling a genealogical database. Show both sufficient cause (severity of the crime) and that the DNA available for comparison is both capable of providing a reliable match and that it has a very high probability of coming from the perpetrator. Also of course that a guilty has to have other corroborating evidence as well.
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Old 19th January 2020, 01:06 PM   #85
Samson
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Originally Posted by ArchSas View Post
Ok boomer.

But more seriously, everyone on this forum really needs to stop assuming their gut reactions and opinions are facts. You guys are ridiculous, it's like I'm back on 4chan sometimes.
I guess if you like "OK boomer", and to be honest that woman is now on 3 times the average wage for taking a position controlling other people's lives, you may be her age.
On familial dna, you might consider it will greatly impact your future and just roll with the thread.
On the forum generally, you will learn far more here than the big social media sites, despite many people having personal grievances against the forum.
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