Continuation Part 2 - Discussion of the Amanda Knox case

[quadraginta]

Seems to be deliberate misunderstanding of what I typed.

Oh,I understood just fine.

When you believe something first, and then select things which support your beliefs ... that's 'rational'. When someone else does the same thing to support beliefs you disagree with ...that's rationalizing.

There is nothing wrong with looking for evidence to support your instincts. This is how science works. It's when you fail to find evidence and then invent the facts you need, that it becomes confirmation bias.

Um, no. That's not quite what confirmation bias is. Just for starters, something doesn't "become" confirmation bias. It either is, or it isn't.

'Inventing the facts you need' isn't confirmation bias, either. That's called 'lying' in many circles.

"Looking for evidence to support your instincts.", OTOH, is confirmation bias.

It isn't "how science works", though.

A scientist will collect data. He may (or may not) develop a hypothesis in the course of that data collection. If a hypothesis should be developed he may test it. The best way to do that is to try to find data or make predictions which do not support the hypothesis. Merely searching for more data which is in agreement with the hypothesis is one of the most fundamental forms of confirmation bias. Almost, but not quite as fundamental as beginning with the conclusion.

In my example of the kitchen knife, the pro-innocence side naturally suspects contamination;

<snip>

"Naturally".



No confirmation bias here. Right?



To paraphrase a worthy quote, I don't think those words mean what you think they mean.

 

[Chris_Halkides]

blood and contamination

Take the case of the alleged "murder weapon" taken from Raffaele's kitchen drawer. If you are convinced of innocence, then this knife can't possibly really be the murder weapon, so we start to look for reasons to think that the DNA reading is from contamination. And we find that the knife was tested in an uncertified laboratory already containing the victim's DNA, by an unrecognised procedure, and that the technician carrying out the test never ran any controls for contamination. Not only that, but the knife was previously removed from the collection envelope by police and placed in a used cardboard box for no discernible reason. So there is more than one route by which it could have been contaminated, but the laboratory procedures alone make the test manifestly meaningless.

Antony,

I would put it a little differently. It is the lack of blood on the knife that makes me believe that the result is more like to be due to contamination, secondary transfer, or tampering than to its being used in a murder. That fact forces the pro-guilt community to posit that the DNA came from some other type of cell. They offer this hypothesis even though that there is no evidence one way or another for the tissue type and even though it is odd that cleaning should remove blood and not the cells that supposedly gave rise to the DNA.

If contamination occurred outside of the lab, it may have happened because the second person to handle the knife had just come from the girls' flat. If it happened inside the lab, the presence of so many items of evidence with Meredith's DNA suggest that it is more likely that contamination would be with Meredith's DNA than anyone else's DNA.

 

[Dan O.]

A scientist will collect data. He may (or may not) develop a hypothesis in the course of that data collection.

That just brings up the image... "Dennis, there's some lovely filth data down here..."


ETA: A review of the Scientific Method^WP might be warranted.

 

[RoseMontague]

Antony,

I would put it a little differently. It is the lack of blood on the knife that makes me believe that the result is more like to be due to contamination, secondary transfer, or tampering than to its being used in a murder. That fact forces the pro-guilt community to posit that the DNA came from some other type of cell. They offer this hypothesis even though that there is no evidence one way or another for the tissue type and even though it is odd that cleaning should remove blood and not the cells that supposedly gave rise to the DNA.

If contamination occurred outside of the lab, it may have happened because the second person to handle the knife had just come from the girls' flat. If it happened inside the lab, the presence of so many items of evidence with Meredith's DNA suggest that it is more likely that contamination would be with Meredith's DNA than anyone else's DNA.

I agree. We know now that starch was also found on the knife blade which also argues against a cleaning. How can you selectively remove the blood yet leave both starch and tissue behind?

 

[Chris_Halkides]

Shimmer

I agree. We know now that starch was also found on the knife blade which also argues against a cleaning. How can you selectively remove the blood yet leave both starch and tissue behind?

I know the answer: magic cleaning fluid.

 

[RoseMontague]

Some facts about the knife:

1. There is no evidence that Raffaele gave his kitchen knife to Amanda for "protection".
2. There is no evidence that Amanda carried this knife around.
3. The knife doesn't fit the imprint on the bed.
4. The knife doesn't fit all the wounds.
5. The knife was found in the kitchen drawer of Raffele's apartment.
6. There was no blood on the knife.

I have not found the theory of why Amanda would be carrying this knife around persuasive at all. I have not found the theory of why after a murder they would place it back in Raffaele's kitchen drawer persuasive at all. I have not found Stefanoni's inventive testing persuasive at all. I don't find the theory that a second knife used in the murder must have belonged to Raffaele very persuasive either.

I believe there is a ton of reasonable doubt that this knife was used in the murder and this doubt approaches a very high probability that the knife was not the murder weapon.

 

[Antony]

Oh,I understood just fine.

When you believe something first, and then select things which support your beliefs ... that's 'rational'.

When did I say anything about "selecting"?

When someone else does the same thing to support beliefs you disagree with ...that's rationalizing.

I think if you'd read this thread you wouldn't be calling shuttlt's "post-hoc rationalisation" as "doing the same thing" as seeking factual verification.

Um, no. That's not quite what confirmation bias is. Just for starters, something doesn't "become" confirmation bias. It either is, or it isn't.

'Inventing the facts you need' isn't confirmation bias, either. That's called 'lying' in many circles.

You're being too hard on yourself. Much of the guilter mythology falls into the category of "unsupported speculation" rather than "lying".

"Looking for evidence to support your instincts.", OTOH, is confirmation bias.

It isn't "how science works", though.

A scientist will collect data. He may (or may not) develop a hypothesis in the course of that data collection. If a hypothesis should be developed he may test it. The best way to do that is to try to find data or make predictions which do not support the hypothesis. Merely searching for more data which is in agreement with the hypothesis is one of the most fundamental forms of confirmation bias. Almost, but not quite as fundamental as beginning with the conclusion.

Bluster. Nowhere have I suggested "searching for more data which is in agreement with the hypothesis". We're talking simply about the pro-innocence side asking the right questions. Both the kitchen knife and the bra-clasp were collected, handled and/or tested in circumstances where contamination was highly likely. That's plain "confirmation" of the innocence case - no "bias" involved.

My point - in fact just as you state in your paragraph above - is that it's legitimate to test your hypothesis by focussing on relevant facts, and that's entirely different from "post-hoc rationalisation" of a conclusion already held.

The further point is that everything you criticise here - ranging from "confirmation bias" (however you understand that) through to outright lying - makes up the substance of the accusations against Amanda and Raffaele from both the official Perugia prosecution and the guilter blogosphere.

 

[Chris_Halkides]

another fact about the knife

RoseMontague,

That is a useful list. I would add:

7. The knife was collected on November 6th. There is no record of any other utensil's being tested.

This last point is relevant for two reasons. First, it opens the question of whether or not confirmation bias was in play. Second, other utensils (yes, even spoons) would have served as a kind of substrate control.

 

[RoseMontague]

Updates on the Sabrina Misseri case (murder of Sarah Scazi). Insanity. The dad (who confessed to murder) has been released because he has already served the 6 months for what he was charged with (concealing the body). The have also arrested Sabrina's mother Cosima for aiding her daughter to kidnap Sarah and conceal the body. Evidently the Mom's DNA was found mixed with Sarah's (she was staying in the same house). Just crazy.

http://bari.repubblica.it/cronaca/2...n_assassino_arrestatemi-16997378/?ref=HREC1-4

http://www3.lastampa.it/cronache/sezioni/articolo/lstp/404857/

 

[JREF2010]

I know the answer: magic cleaning fluid.

thats not really funny in this court.

how many other key pieces of the prosecutions false accusations have been tossed out, and yet the creative theory's seem endless and convincing to the jurors?

the circles of the shoes left optimism without action, Raffaele was not let go.
the 112 call, even the Judge realizes was made before the Postal arrived but that didnt change the guilty verdict.

the knife might be tossed into the pile of garbage evidence, but the pro-guilt will just readjust the guilt theory. maybe it was Raffaele serving the fatal wounds, and Amanda with her ears covered and Rudy telling the truth.

I know its pessimistic for the defense, but if the courts allow a creative freedom in every trial then there may not be enough trials for the defense to confront all of the theory's the prosecution creates.

really, if they can place Amanda in Merediths bedroom without one picogram of evidence then it seems science isn't a main factor in this equation for truth.

 

[Chris_Halkides]

Updates on the Sabrina Misseri case (murder of Sarah Scazi). Insanity. The dad (who confessed to murder) has been released because he has already served the 6 months for what he was charged with (concealing the body). The have also arrested Sabrina's mother Cosima for aiding her daughter to kidnap Sarah and conceal the body. Evidently the Mom's DNA was found mixed with Sarah's (she was staying in the same house). Just crazy.

http://bari.repubblica.it/cronaca/2...n_assassino_arrestatemi-16997378/?ref=HREC1-4

http://www3.lastampa.it/cronache/sezioni/articolo/lstp/404857/

RoseMontague,

Thanks for the update. Here is another link (Scazzi is with two z's). This is beyond comprehension. However, it does highlight the important point that DNA evidence can be misunderstood. As several of us have said many times before, DNA does not come with a time stamp, and mixed DNA is not especially unusual.
ETA
I am glad that ILE cannot test the Mellas household for DNA; Sabrina's mother recently protested her daughter's innocence.

 

[babycondor]

On the night of the murder, were there two bedsheets on Meredith's bed, or just one? Charlie posted these selective results of tests here some time ago:

See HERE: DNA RESULTS

In that document "Rep 63" refers to samples taken from a white bed sheet, while "Rep 123" and "Rep 124" refer to samples taken from a matress cover.

Is this white bed sheet what normal people would call a top bedsheet, and is this matress cover what normal people would call a bottom, fitted, bedsheet?

///

It is hard to be certain given the problems of translation, but from the crime scene photos, I would say the white sheet visible on the bed (what I call a fitted bottom sheet) is the only proper sheet in the photo. No top sheet is visible. (The duvet would have served as the only top cover, I suppose.)

The "fragment of mattress cover" could refer to what I would call a "mattress pad" that sometimes is placed on top of a mattress between the mattress and the bottom sheet. This cover may or may not be "fitted." I can't tell from the photo whether her bed had one of these on it.

The "mattress cover" could also refer to the "ticking," the fabric cover that holds the mattress parts inside it.

 

[RoseMontague]

RoseMontague,

Thanks for the update. Here is another link (Scazzi is with two z's). This is beyond comprehension. However, it does highlight the important point that DNA evidence can be misunderstood. As several of us have said many times before, DNA does not come with a time stamp, and mixed DNA is not especially unusual.

I am not sure if your post should read "misrepresented" instead of "misunderstood". I am trying to find more on the exact nature of the DNA evidence that led to the Mom's arrest but have not had much success to this point.

Michele was coerced into naming his daughter and the evidence against her amounts to smoke and mirrors. I had thought the hammer of injustice would fall on the boyfriend next. I was not correct with that one.

 

[Fine]

Was the presumptive blood fake blood?

It's been photo-shopped out. In the first several weeks after the crime, a lot of pictures of Meredith with vampire blood were published, but eventually the press realized it wasn't appropriate, and cleansed the pictures.

____________________

Mary,

Another thought.

The pictures were cleaned using software. That's not how Meredith's face and neck were cleaned. Apparently the real fake blood, so-to-speak, "still dripping from her chin," was cleaned from Meredith on the afternoon of November 1st by taking a shower. That's the impression that Amanda conveyed in her court testimony. Since Amanda had showered earlier that day, also at the cottage, that would mean that Meredith was the last to shower before Amanda's shower on the next day, November 2nd. Meredith's fake blood, diluted, may be what Amanda tracked out of the shower prior to her bathmat boggie.

__________
A common recipe for home-made fake blood: 1/4 ketchup, 3/4 corn syrup. Corn can create a false positive reaction to Luminol.

///

 

[Chris_Halkides]

luminol and cleaning products

Meredith's fake blood, diluted, may be what Amanda tracked out of the shower prior to her bathmat boggie.

__________
A common recipe for home-made fake blood: 1/4 ketchup, 3/4 corn syrup. Corn can create a false positive reaction to Luminol.[1/QUOTE]
Fine,

Some household products can also give false positives. Just a hunch, but I might suspect ketchup more than corn syrup. It depends on how high the level of peroxidases are in tomatoes.
ETA
A study by Tobe et al. (J Forensic Sci, January 2007, Vol. 52, No. 1) saw no reaction between luminol and any plant products, including tomatoes and horseradish. The latter is contrary to expectation based on the known chemistry of horseradish peroxidase, and the authors suggest it might have to do with the drying time of the vegetable matter. Metal salts do give a positive luminol result. These authors also wrote about an extreme dilution of a commercial preparation of luminol, "This was not found to be consistent with this study as luminescence was detected at 1:100,000 dilution of blood in water, 100 times more sensitive than what is claimed by the company. This luminescence was faint and short-lived, but was still detectable."

 

[Chris C]

____________________

Mary,

Another thought.

The pictures were cleaned using software. That's not how Meredith's face and neck were cleaned. Apparently the real fake blood, so-to-speak, "still dripping from her chin," was cleaned from Meredith on the afternoon of November 1st by taking a shower. That's the impression that Amanda conveyed in her court testimony. Since Amanda had showered earlier that day, also at the cottage, that would mean that Meredith was the last to shower before Amanda's shower on the next day, November 2nd. Meredith's fake blood, diluted, may be what Amanda tracked out of the shower prior to her bathmat boggie.

__________
A common recipe for home-made fake blood: 1/4 ketchup, 3/4 corn syrup. Corn can create a false positive reaction to Luminol.

///

Or it could just have easily been Meredith who tracked it out.

 

[Mary_H]

____________________

Mary,

Another thought.

The pictures were cleaned using software. That's not how Meredith's face and neck were cleaned. Apparently the real fake blood, so-to-speak, "still dripping from her chin," was cleaned from Meredith on the afternoon of November 1st by taking a shower. That's the impression that Amanda conveyed in her court testimony. Since Amanda had showered earlier that day, also at the cottage, that would mean that Meredith was the last to shower before Amanda's shower on the next day, November 2nd. Meredith's fake blood, diluted, may be what Amanda tracked out of the shower prior to her bathmat boggie.

__________
A common recipe for home-made fake blood: 1/4 ketchup, 3/4 corn syrup. Corn can create a false positive reaction to Luminol.

///

Very interesting thought, Fine. Chris makes a good point, too. Wouldn't it be ironic (no pun intended) if it were Meredith's footprint?

 

[Mary_H]

That just brings up the image... "Dennis, there's some lovely filth data down here..."


ETA: A review of the Scientific Method^WP might be warranted.

Thank you, Dan. I suppose one could say, in the broadest sense, that a scientist collects data and then forms a hypothesis. Don't we all? It's called learning. Testing our hypotheses is where science comes in.

 

[Mary_H]

Meredith's fake blood, diluted, may be what Amanda tracked out of the shower prior to her bathmat boggie.

__________
A common recipe for home-made fake blood: 1/4 ketchup, 3/4 corn syrup. Corn can create a false positive reaction to Luminol.[1/QUOTE]
Fine,

Some household products can also give false positives. Just a hunch, but I might suspect ketchup more than corn syrup. It depends on how high the level of peroxidases are in tomatoes.
ETA
A study by Tobe et al. (J Forensic Sci, January 2007, Vol. 52, No. 1) saw no reaction between luminol and any plant products, including tomatoes and horseradish. The latter is contrary to expectation based on the known chemistry of horseradish peroxidase, and the authors suggest it might have to do with the drying time of the vegetable matter. Metal salts do give a positive luminol result. These authors also wrote about an extreme dilution of a commercial preparation of luminol, "This was not found to be consistent with this study as luminescence was detected at 1:100,000 dilution of blood in water, 100 times more sensitive than what is claimed by the company. This luminescence was faint and short-lived, but was still detectable."

I have read that it is the cyanates in the vegetable matter (like horseradish, leaves, etc.) that react with the luminol. Do any of these substances contain cyanates?

Homemade Fake Blood
1 c. Karo Syrup
1 Tbsp Water
2 Tbsp Red Food Coloring
1 tsp Yellow Food Coloring
Mix together in a mixing bowl and you're done. Try adding blue or yellow for a different shade.

Chocolate Fake Blood
1/2 c. Warm Water
4 Tbsp Corn Syrup
1 Tbsp Powdered Cocoa
1 tsp Red Food Coloring
Blend the water and cocoa together and then add the rest of the ingredients. Let the concoction sit for awhile and skim the bubbles off of the top. Add a couple of drops of yellow food coloring if you're not satisfied.

Simple Fake Blood
Clear Corn Syrup
Red Food Coloring
Milk - Optional
However much fake blood is how much corn syrup you'll need. Pour it into a bowl and mix in some red food coloring. Add some blue if you like. Adding a small amount of milk will make the blood appear darker and thicker.

Realistic Recipe
2/3 c. Corn Syrup
1/3 c. Warm Water
5 Tbsp Corn Starch
4 tsp red food coloring
1 Tbsp Powdered Cocoa
2 drops of green or yellow food coloring
Mix the corn starch with the water in a large mixing bowl. Stir in the corn syrup. Add the food coloring slowly.

Gravy Blood
This is fairly new and I haven't had chance to test it properly but its looks GREAT!
Gravy Granules
Red Food Coloring
HOT Water
The directions are EASY, all you do is make the gravy up as you would normally but if you feel like it, you can make it a bit thicker, then add the red food coloring. It's up to you how much you add but too much will stain as it will not have been diluted enough.

Cheap 'N' Easy Blood
This is good for spidering:
Plain Flour
Water
Red Food Coloring
1 tsp. of Coffee
Boil the water on the stove, then sieve in the flour, making sure you get ALL of the lumps out. The quantity of ingredients aren't important, it just depends on how much you want. Once you have the flour mixed nicely into the water it should look nice and thick. Next, add the red food coloring.

You will notice that it's a ghastly, bright red colour but don't worry this is why we add the coffee. It is important that when you add the coffee to make sure the mixture is hot, otherwise it wont dissolve, but up until adding the coffee can be done in a ordinary mixing jug or pan.

Palmolive Imitation Blood
You can also make fake blood with Palmolive dish soap, (it doesn't matter how much you put in) it depends on how much blood you want! Add red berry powdered Kool-Aid!

http://acapella.harmony-central.com...-dye-that-doesn-t-stain-(Fake-blood-content!)

 

[Chris_Halkides]

horseradish peroxidase

I have read that it is the cyanates in the vegetable matter (like horseradish, leaves, etc.) that react with the luminol. Do any of these substances contain cyanates?

Mary_H,

Horseradish and turnips have abundant amounts of an enzyme known as peroxidase (really a family of enzymes). The cyanate issue is new to me. Do you have a citation?