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22nd July 2020, 04:49 PM | #121 |
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mind the gap
"Mr Yovich also referred to a contamination event that occurred in a UK lab in 2007, when an ex-employee’s DNA was detected on a DNA test negative control blank 16 months after they had resigned...Having read the incident report, Justice Hall clarified with Mr Yovich during his cross-examination of Dr Whitaker that the contamination could have occurred while the employee was still in the lab, but was not detected until later." link
The quote above is from an article on the Claremont murder case. Either way the DNA persisted. I would point to the Annie Le case as an example of DNA persisting in a less than pristine environment. Ms. Lee was a graduate student who was murdered by Raymond Clark. Another person's DNA was found on one sample from her underwear. |
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24th July 2020, 04:52 AM | #122 |
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You have to separate two things, DNA of an employee and DNA of a sample.
Unlike samples, employees tend to walk around and deposit their genetic material on everything they touch. This is unavoidable, there is your DNA on your mouse, phone, on the door knob you used, toilet seat, everywhere. This is a fact of life and forensic laboratories are well aware this is a possibility (and is a major reason why DNA testing is such a great tool). What likely happened here is that the employee in question left their DNA on a piece of equipment or consumables that wasn't used until many months later. DNA can persist there, this is not a question, but the object in question was not used, that's why the contamination wasn't picked up until much later. If I had to guess I'd say it might've been a pipette that the employee liked to use but other employees for whatever reason did not. Over a year later someone used that pipette for whatever reason and found the contamination. Other possibilities include consumables that were ordered in bulk and the employee in question stored (and hanlded them impropertly) or something of that nature. It wasn't something routinely in use that just happened to deposit their DNA 16 months later, but it could've happened at any time prior. This doesn't happen, something was done differently in that run to all the others. Samples, by the virtue of being, well "not alive", are much more inert and do not deposit themselves all over the place. This is especially true for a known sample contaminating an unknown sample, because there are multiple safeguards aimed at preventing exactly that scenario. The point is, an employee leaving a trace of their DNA is not an indication the same could happen to a sample. The contamination probably happened outside of clean area where samples are handled. In either event it is not an indication of a known sample contaminating another known sample as being possible, let alone likely. Again, random chance should be mentioned. Suppose all this happens, what are the odds that a known sample contaminating something that would implicate this particular person? A laboratory processes hundreds of unknown samples each week, if this two events happened months apart you're talking about odds of well under 0.01% - and that is assuming the cross-contamination did happen (which is infitesemal). It's far more likely some random sample unconnected to the case would be contaminated than this particular sample would. I mention this because for this to have any merit at all, one would expect it happens in the laboratory with some regularity before it becomes relevant. If there is no indication such a contamination is a problem the laboratory grapples with, then police framing is a better explanation than accidental contamination. McHrozni |
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24th July 2020, 05:04 AM | #123 |
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As far as I'm concerned, DNA should be thrown out of Knox/Sollecito case. Yes, stutter peaks are a (known) problem.
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But this is not oversight. It's a good reason why you would want to rotinely consult a lawyer (and maybe a prosecutor) to inspect the laboratory, find possible faults to use in courts and correct them to their satisfaction, or explain why that is impossible. Oversight is a far more encompassing term that would see lawyers tell forensics what to do and how. This is not possible, most forensics are better versed in law than lawyers are in forensics. Lawyers can be useful to find potential holes you can plug before they become relevant, though not as oversight.
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McHrozni |
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28th July 2020, 02:38 PM | #124 |
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faking the negative controls
Replacing the true electropherogram with another, in order to misrepresent the negative control as being clean is a class of misbehavior that one should distinguish from either evidence tampering or carelessly cross-contaminating samples IMO. For example it might be motivated for reasons such as the fact that re-running a whole batch would cost time and money. Another reason is that all of the sample might have been consumed. I don't disagree that it is a serious matter.
I was not able to find electropherograms for the Avery case, but I did find some useful information, which I put into comment #99 in the Avery/Dassey thread. |
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29th July 2020, 08:17 PM | #125 |
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case of Gary Leiterman
In her book Inside the Cell, Professor Erin Murphy wrote (p. 57) "Leiterman's sample came into the laboratory on February 22, 2002; the evidence in Ruelas's case was processed the day before. Leiterman's sample was first analyzed between July 17 and July 23; Ruelas's reference sample was submitted on July 19 and then sent to an outside lab for testing. The Mixer evidence was processed at the lab between March 26, 2002 and April 9, 2002"
Ruelas's DNA on one of the Mixer items is an obvious case of laboratory contamination; that the same might be true of Leiterman's DNA has been pointed out both by Dr. Kessis and Professor Krane. |
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29th July 2020, 08:23 PM | #126 |
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the cold case of Jane Durrua
"Two years after Bellamy’s arrest, investigators discovered that evidence from the murder scene had been contaminated by DNA from [Jerry] Bellamy, whose genetic sample was being tested at the same lab in an unrelated case. He was freed. Another man ultimately was arrested but died before trial." Link. I also dealt with this case briefly at my blog. Unfortunately, at leas one of the links there is dead.
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20th September 2020, 10:56 AM | #127 |
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Verdict is due on Tuesday.
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20th September 2020, 12:02 PM | #128 |
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comparison to the Swearingen case
In the Larry Swearingen thread we discussed the laboratory's claim that a particle of dried blood contaminated the fingernail sample of the victim; there was no evidence of this, but it was convenient for the prosecution's case. I am puzzled that laboratory contamination is asserted to be rare in one case and likely in another.
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21st September 2020, 12:35 PM | #129 |
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I was wondering about that too. I don't know if there are any reasonable grounds for thinking the likelihood of contamination would be different in the two cases, versus confirmation bias.
I did try thinking about how to get some estimate of probability of contamination in the Claremont case and how it would work in a likelihood ratio compared to this one, looking at the Leiterman case, but gave up on it for the moment as it was doing my head in. I got the dates a bit mixed up; verdict is actually due on Thursday. |
22nd September 2020, 12:45 AM | #130 |
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23rd September 2020, 06:56 PM | #131 |
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Guilty of two charges but not guilty of killing Sarah Spiers. I will post a link when a good one comes up.
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23rd September 2020, 06:59 PM | #132 |
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https://www.news.com.au/national/cou...b38c6241f450a2
In a bombshell verdict, the 51-year-old Telstra technician accused of being the Claremont serial killer has been found guilty of two of three murders of young women in 1996 and 1997.
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24th September 2020, 07:49 AM | #133 |
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It seems like a just verdict to me. As Supreme Court Justice Stephen Hall noted, the fibre and DNA evidence together sealed Edward's fate on Jane Rimmer and Ciara Glennon.
As sad as it is for the Spiers family, the absence of any direct evidence pointing to Edwards and only the mere coincidence that she disappeared from the same area at around the same period of time meant that the Justice Hall could not convict Edwards of the Sarah Spiers murder. |
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24th September 2020, 03:10 PM | #134 |
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A fanatic is one who can't change his mind and won't change the subject. Sir Winston Churchill |
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1st October 2020, 04:06 PM | #135 |
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I was reading the closing arguments in the last days of the trial, and I noticed Justice Hall was seemed quite open about indicating which way his thoughts were going. He appeared to reject some statements of the defence regarding the DNA sample, and was pressing the prosecution for reasons why he should accept it as proven BARD that the person who murdered Ciara Glennon and Jane Rimmer also murdered Sarah Spiers, rather than just being highly likely.
I am still puzzled by the lack of a robust defence (in terms of calling experts) to challenge the DNA and fibre evidence. |
1st October 2020, 05:27 PM | #136 |
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you are not the only one
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It is possible both to be right about an issue and to take oneself a little too seriously, but I would rather be reminded of that by a friend than a foe. (a tip of the hat to Foolmewunz) |
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13th October 2020, 04:51 AM | #137 |
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Edwards was convicted of attacking a social worker inside Hollywood Hospital in 1990. He apparently attacked her in her office without warning from behind, and tried to force a gag into her mouth. Hollywood hospital is opposite Karrakatta cemetery, the site of the 1995 rape Edwards confessed to at trial. I believe police always suspected this rape was connected to the Claremont murders, even before any physical evidence, due to the location and manner of the abduction. It seems a significant oversight that nobody connected Edwards' assault conviction to this rape, at the time or even more so after the murders in the next two years. He was only convicted of common assault, although he was ordered to undergo a program for sex offenders, so obviously somebody recognised something rather more sinister in the attack.
This might have been related to the obsession the police had with going after the wrong man. Another strange aspect is that Edwards kept his job at Telstra, after being convicted of assaulting a woman while working for them as a technician. |
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