Amanda Knox tried for the murder of Meredith Kercher in Italy *NEW TRIAL*#12

[sherlockh]

http://tritechforensics.com/store/product/tetramethylbenzidine-tmb-blood-test-kit/#readmore

Because TMB is more sensitive than phenolphthalein. That is not the case with Luminol.

 

[otto]

Because TMB is more sensitive than phenolphthalein. That is not the case with Luminol.

Kastle‐Meyer Test –Limitations
Kastle‐Meyer (Phenolphthalein)
TMB is not as specific as KM test

Sensitivity
− 1 in 1000 on dried stains

Specificity
− Can weed out false positives between steps 2 and 3
− Chemical oxidants, vegetable peroxidases
− Will not detect differences in animal or human blood

Stability
− Relatively stable if the reagents are stored separately and refrigerated

http://projects.nfstc.org/bsw/presentations/02_BioScreening_Blood_012010_CBS_JMS.pdf ; pages 23, 46

 

[sherlockh]

TMB is a confirmatory test for blood. If there is a blood stain, it is the best method for identifying whether it is blood. Luminol is used as a reconstruction tool, to identify the paths and activities taken by the culprits. It can dilute the sample.

Was the TMB test performed on blood that was revealed with luminol, or on original blood collected on the day of the murder? If TMB was applied to a sample that had been revealed with luminol 46 days after the murder, there's less chance that it would test positive for hemoglobin. That doesn't mean that it is not blood.

That's my understanding from what I've read.

Even if the TMB test had been positive it would still not have confirmed the blood, because TMB has some of the same false positives as Luminol.

 

[otto]

Sensitivity Scale

Kastle‐Meyer (Phenolphthalein) 1:1000
Leucomalachite Green (LMG) 1:1000
Tetramethylbenzidine (TMB) 1:10,000
Luminol 1:1,000,000 to 1:100,000,000

http://projects.nfstc.org/bsw/presentations/02_BioScreening_Blood_012010_CBS_JMS.pdf
http://projects.nfstc.org/bsw/

 

[otto]

Thank you! So can we stop calling TMB a confirmatory test please? I am not sure why that dr is not considering Luminol, because TMB is certainly not more sensitive than Luminol. Not even close.

I think the word "confirmatory" is creating confusion. When I first read it, I had to think about what it meant, so I read up a bit more. My understanding is that the primary use, or application, for TMB is to confirm that a clean blood sample is blood; that it contains hemoglobin. The test is less reliable if it is applied to a sample that has been tested with Luminol. It's usefulness deteriorates with time (can someone double check that: very unstable, one week maximum, loses sensitivity by a factor of 10 after one day; pg48)

TMB confirms the presence of hemoglobin in a clean blood sample.

Luminol is used to track blood that has deteriorated, disappeared with time, or been cleaned up. What does exposure to air over 46 days do to hemoglobin? Luminol reveals blood evidence useful for crime scene reconstruction, TMB confirms hemoglobin in a clean blood sample.

 

[otto]

Even if the TMB test had been positive it would still not have confirmed the blood, because TMB has some of the same false positives as Luminol.

Thank you. That's my understanding as well. After Luminol has been applied, the sample is compromised.

Luminol –Limitations

Stability
− Very unstable
− About eight hour limit

Mostly used at crime scene
− Can dilute out stain (possibly too much for DNA analysis) [and identification of blood]
− Used more for blood spatter, crime scene reconstruction

 

[MichaelSmith]

Let's look at the numbers from the US Justice Department in 2013:

10-6 would be 10 to the power of negative 6, which would be: 1:1,000,000 or 0.000010

10-8 would be 10 to the power of negative 8, which would be 1:100,000,000 or 0.00000010

It is in fact 1:100,000,000

Who are these people? This information is not from the US Department of Justice or a federal law enforcement agency or scientific study about luminol. This is some small group of people who give presentations and do training and online courses living off a government grant. This should be taken with a grain of salt.

©2013 National Forensic Science Technology Center ® NFSTC Science Serving Justice® 7881 114th Avenue North • Largo, Florida 33773 | (727) 549-6067 • info@nfstc.org

This web site is funded through a grant from the Bureau of Justice Assistance, the National Institute of Justice, and the Office of Juvenile Justice and Delinquency Prevention, Office of Justice Programs, US Dept. of Justice. Neither the US Dept. of Justice nor any of its components operate, control, are responsible for, or necessarily endorse this web site (including, without limitation, its content, technical infrastructure, and policies, and any services or tools provided).

 

[otto]

Who are these people? This information is not from the US Department of Justice or a federal law enforcement agency or scientific study about luminol. This is some small group of people who give presentations and do training living off a government grant. This should be taken with a grain of salt.

©2013 National Forensic Science Technology Center ® NFSTC Science Serving Justice® 7881 114th Avenue North • Largo, Florida 33773 | (727) 549-6067 • info@nfstc.org

This web site is funded through a grant from the Bureau of Justice Assistance, the National Institute of Justice, and the Office of Juvenile Justice and Delinquency Prevention, Office of Justice Programs, US Dept. of Justice. Neither the US Dept. of Justice nor any of its components operate, control, are responsible for, or necessarily endorse this web site (including, without limitation, its content, technical infrastructure, and policies, and any services or tools provided).

If the sensitivity of Luminol is not 10 to the power of negative 6 to 10 to the power of negative 8, what is it? Are all of the numbers incorrect, or only Luminol?

That is, of the four methods for analysing blood evidence, are all the probabilities incorrect, or only the Luminol probability, and what is the correct number? A link would be helpful.

What is the probability that this group would receive Federal Justice Department Grants if they were blowing smoke up?

 

[MichaelSmith]

If the sensitivity of Luminol is not 10 to the power of negative 6 to 10 to the power of negative 8, what is it? Are all of the numbers incorrect, or only Luminol?

That is, of the four methods for analysing blood evidence, are all the probabilities incorrect, or only the Luminol probability, and what is the correct number? A link would be helpful.

It's a con trying to pass that site off as a credible cite about luminol sensitivity in forensic serology. I was almost fooled thinking it was something from the government but it's certainly not.

 

[aa9511]

The DNA did not necessarily EVER come into contact with the knife. It could have easily come from the lab where the testing took place. Remember. that same lab conducted tests on a much larger quantity of MK's DNA just 6 days earlier to serve as a reference against which evidence could be tested. At least part of the equipment used to test the knife probably was the same equipment used 6 days earlier. Is it such a stretch to imagine that an "itty-bitty piece" of the DNA used as a standard remained on the equipment and contaminated the sample swabbed from the knife? In most Western justice systems it is the responsibility of the prosecution to prove evidence they present is solid and DNA evidence is not contaminated. In this case the ISC appears to have reversed the burdon of proof and said that it is the defenses burdon to prove contamination. This is a real catch-22 since it is next to impossible to prove contamination after the fact whereas the prosecution could have proven no contamination at the time of the study if they had done 2 samples and performed the expected control experiments.

Can you tell me, how many samples from the knife, in total, were tested (if you know)? I would assume that more than just the 2 (Meredith DNA, Amanda DNA) were tested.

If it was contamination, wouldn't we have seen Meredith's DNA in more of the samples? How come it managed to land on just this one?

 

[sherlockh]

I think the word "confirmatory" is creating confusion. When I first read it, I had to think about what it meant, so I read up a bit more. My understanding is that the primary use, or application, for TMB is to confirm that a clean blood sample is blood; that it contains hemoglobin. The test is less reliable if it is applied to a sample that has been tested with Luminol. It's usefulness deteriorates with time (can someone double check that: very unstable, one week maximum, loses sensitivity by a factor of 10 after one day; pg48)

TMB confirms the presence of hemoglobin in a clean blood sample.

Luminol is used to track blood that has deteriorated, disappeared with time, or been cleaned up. What does exposure to air over 46 days do to hemoglobin? Luminol reveals blood evidence useful for crime scene reconstruction, TMB confirms hemoglobin in a clean blood sample.

Actually, it does not really matter what you call it. The point is that a less sensitive test can never overrule a more sensitive test. This goes for any test. So I learned a lot about Luminol and TMB but at the end of the day the results are inconclusive, and we are left with a test result that indicates the presence of blood but could not be confirmed. Then it is up to the judge if he accepts the Luminol evidence or not, and he did with the notice that it could be something else, but after considering 'something else' came up with the conclusion that it was blood. I never really understood why this would be a problem.

 

[otto]

It's a con trying to pass that site off as a credible cite about luminol sensitivity in forensic serology. I was almost fooled thinking it was something from the government but it's certainly not.

My research confirms the numbers.

Since you disagree, could you please provide the correct numbers, ratios, probabilities and a link. Thx

I think the claim that a website, wiki, or journalist is "not a credible cite [citation]" is tired and invalid.

 

[otto]

Actually, it does not really matter what you call it. The point is that a less sensitive test can never overrule a more sensitive test. This goes for any test. So I learned a lot about Luminol and TMB but at the end of the day the results are inconclusive, and we are left with a test result that indicates the presence of blood but could not be confirmed. Then it is up to the judge if he accepts the Luminol evidence or not, and he did with the notice that it could be something else, but after considering 'something else' came up with the conclusion that it was blood. I never really understood why this would be a problem.

At least all possibilities were explored prior to concluding that the blood on the floor was blood on the floor. It's funny how the law has forced us to doubt what is obvious until it is proven by some sort of debatable scientific method.

Luminol revealed that Guede ran directly from Meredith's bedroom out the front door. It also revealed that Knox stood facing Meredith's bedroom door and left some prints in the hallway. She left a confirmed DNA sample mixed with blood in Filomina's bedroom.

Luminol illustrated the paths taken by the culprits, but there is no explanation for Sollecito's 3/4 bare footprint on the bathmat, unless Knox shuffled the mat towards Meredith's bedroom for Sollecito so he could step on the bathmat between Meredith's bedroom and the bathroom.

What tested positive with TMB? Was that the sample in Filomina's bedroom, and in the bathroom? The blood dripping down the edge of the bathroom door should have been evident to anyone walking down the hall, or entering the bathroom. Did that test positive for hemoglobin with TMB?

 

[aa9511]

Sensitivity Scale

Kastle‐Meyer (Phenolphthalein) 1:1000
Leucomalachite Green (LMG) 1:1000
Tetramethylbenzidine (TMB) 1:10,000
Luminol 1:1,000,000 to 1:100,000,000 http://projects.nfstc.org/bsw/presentations/02_BioScreening_Blood_012010_CBS_JMS.pdf
http://projects.nfstc.org/bsw/

bbm

LOL....well that kind of clears up that issue, IMO.

 

[otto]

What was used in the bathroom? Was it one of the 1:1000 tests?

 

[otto]

bbm

LOL....well that kind of clears up that issue, IMO.

I suppose it's possible that educational seminars funded by Federal Justice Department Grants in 2013 could be a problem, but I'm curious why.

The original link works. It's an educational site funded by the federal justice government grants as far as I can see.

What is the problem with the website? The reference is legitimate. Of course there's a disclaimer, every website has one. It's symposiums and seminars about forensics. Should we distrust the information because the website is sustained with a Federal Justice Department Grant?

 

[otto]

I think it's time for you and Sherlock to cite some legitimate sources and scientific studies about luminol not fancy pdf's from some mob who offer online courses.

I'm reading backwards.

I understand that you disagree with the validity of the linked source, but did you post the true probability of Luminol Sensitivity and I missed it? If the seminar notes in the linked source have mistakes, please post corrections so we can all learn something.

Where is our resident Chemist when we need him?

 

[otto]

I think it's time for you and Sherlock to cite some legitimate sources and scientific studies about luminol not fancy pdf's from some mob who offer online courses.

Have you considered the possibility that job training is in the from a 3 hours ppt seminar in slide format made available through federal government grants as part of a certification program?

"The National Forensic Science Technology Center (NFSTC) is dedicated to supporting the justice and defense communities through innovative programs, evaluation of the latest technologies, training, laboratory support and consulting. Our goal is for all stakeholders to receive and provide the highest level of forensic science services.
...

NFSTC has a long history of partnering with academic institutions to help build or enhance college curricula via online courses, subject matter expertise, practical lessons and skill assessments.
...

NFSTC partner FIC wins coveted Brandon Hall award
The Forensic Innovation Center, LLC (FIC), a partner firm of NFSTC, along with Sealund and Associates, has been selected by Brandon Hall to receive the silver Excellence in Technology award for Best Advance in Gaming or Simulation Technology"



http://www.nfstc.org/

 

[otto]

I think these ratios are correct, and barring any links explaining more correct numbers, we should accept this information, and federally funded forensic training materials websites, as valid. If this information is wrong, I'm confident that everyone wants a link to the correct information.

Sensitivity Scale

Kastle‐Meyer (Phenolphthalein) 1:1000
Leucomalachite Green (LMG) 1:1000
Tetramethylbenzidine (TMB) 1:10,000
Luminol 1:1,000,000 to 1:100,000,000

http://projects.nfstc.org/bsw/presentations/02_BioScreening_Blood_012010_CBS_JMS.pdf
http://projects.nfstc.org/bsw/

 

[MichaelSmith]

Have you considered the possibility that job training is in the from a 3 hours ppt seminar in slide format made available through federal government grants as part of a certification program?

"The National Forensic Science Technology Center (NFSTC) is dedicated to supporting the justice and defense communities through innovative programs, evaluation of the latest technologies, training, laboratory support and consulting. Our goal is for all stakeholders to receive and provide the highest level of forensic science services.
...

NFSTC has a long history of partnering with academic institutions to help build or enhance college curricula via online courses, subject matter expertise, practical lessons and skill assessments.
...

NFSTC partner FIC wins coveted Brandon Hall award
The Forensic Innovation Center, LLC (FIC), a partner firm of NFSTC, along with Sealund and Associates, has been selected by Brandon Hall to receive the silver Excellence in Technology award for Best Advance in Gaming or Simulation Technology"



http://www.nfstc.org/

This is why I have warned people multiple times about the fake wiki and how deceptive it is. The link to that pdf has been used repeatedly by Sherlock as a cite for luminol and TMB sensitivity and I now discover it's what they use on the wiki site. The PDF doesn't even cite any scientific studies. It's a con.

I checked the knife page on the wiki/blog linked here earlier and none of the claims on that page are cited either. Click on the footnote links and they open the mission statement page.