Given how little you understand of presumptive and confirmatory tests, I had assumed you chose not to respond.
1. Why is Meredith's DNA absent from the majority of the luminol-positive areas?
Because they were too diluted, had a too prolonged exposure to light (as it happened with blood traces in the murder room too), the swabs were not always taken exactly from where the prints were, because the floor had been washed with detergent and because the amount of DNA collected by swabs anyway was minimal.
However, Meredith's DNA was recovered from 3 of the 9 visible luminol stains.
2. Why was no true confirmatory test done?
observation i) It is not clear what the adjective "true" means in this statement.
ii) there is actually no evidence that blood tests were not done
iii) the question is irrelevant
3. Why did the luminol-positive areas test negative by TMB, given that the lower limits of detection of the two reagents are so similar?
i) here there is just a false statement; that the practical limits of detection are "similar" is contradicted by experimental studies, such as: Todd et alt; Webb et alt; and other publications recently quoted on this forum. It is
not true that the thresholds are similar; there is literature that found results contrary to that.
ii) in reality TMB in practical use is less sensitive than luminol and indirect, leading to a difference of factor in the magnitude of 10(2)
iii) TMB is also less specific than luminol
iii) TMB reacts to the
same substances that is to the
same false positives; no
known, plausible substance exists that has the power to react with luminol and not with TMB
4. Why do some jurisdictions (several states in the U.S. and at least one in Australia) not even allow luminol evidence into the courtroom without supporting information, while others allow it in but acknowledge that luminol is only presumptive?
This is twisted information from rules of jury-based jurisdictions that you apparently wish to transplant (after twisting it) in other systems. This oblique point has no content, it is irrelevant. Those kinds of reference do not answer to the points that circumstantial evidence needs to be answered if you want to challenge it.
5. Is there any jurisdiction that treats luminol as a confirmatory test?
It's completely irrelevant and out of context. We are not talking about confirmatory tests here, we are not talking neither about "confirming" nor about just a substance. We are talking about pieces of circumstantial evidence.
6. What evidence rules out iron, manganese, or other transition metal ions as the source of the luminol reactivity?
Again it's irrelevant. There is no tests that ever "ruled out" a specific substance, but in evidence assessment process, there is no need to rule out specific substances. The point is that the burden is reversed: there is a need to have a plausible alternative substance and a plausible alternative dynamic, in order to undermine and dismiss the piece of circumstantial evidence.
A link between luminol prints and blood is already expressed by the analogy of features and same context of the luminol prints with the bathmat bare footprints in diluted blood; also, as well as by the peculiarity of the traces themselves, by the coincidence with one of Guede's shoeprints and by other information such as Knox's statements.
And there is no plausible substance containing metal ions. No such substance was detected inside the flat (and all bottles and substances present are recorded); the substances containing metal salts are usually toxic and not for direct human use (enamels, varnishings, gardening products) while the prints are of bare feet. Those alternative substances would react to TMB as well, but they are just not probable nor plausible, there is no evidence of their existence anywhere in the house, and there is no plausible or known dynamic for how a pattern of prints with that set of peculiar features would have been produced in any metal based substance.
7. What errors did Virkler and Lednev make in their conclusion that the areas were probably not blood?
I have no clue of what Virkler and Lednev said.
8. Who made Rep. 180? If it is Amanda's track, then why doesn't the second toe match? If it is not Amanda's track, then what reason is there to suppose that the substance in question is blood?
I don't know why the "second toe" doesn't match, but I can infer that if it's Knox's print, it might be the mark from a drop and not from direct contact. I can also note that the "second toe" in question was never discussed with prosecution's witnesses: when Rinaldi testified, he matched the print to a probable identity with Knox, while none of the defence questioned him about the "second toe".
Obviously it makes no sense to split the question 'whether it is blood' from the rest of the questions. It's worth recall that several prints however can't be matched with sufficient reliability with anyone, but anyway three of them are in Knox's room.
9.Why are there only right feet? When and how were the tracks made?
Because the person/s was/were dragging himself/herself on a bathmat and/or an equivalent piece of fabric.
10. Did the overapplication of luminol cause a false positive?
No, it's impossible. The overapplication itself can give autoluminescence as a residual effect, but cannot give to autoluminescence the shape of human feet.
11. Should the overapplication of luminol reduce one's confidence in the people doing and analyzing this test?
No, not at all.
12. What substance caused the luminol-positive reactions in Sollecito's flat?
Blood.
13. Why do so many forensic writers call for a colorimetric test (such as TMB) to follow a luminescent test (luminol or fluorescein)?
All tests serve the same purpose: collect as more information as possible, when it's possible.
The reason why TMB is suggested (by some, but not all authors) is not because it is colorimetric, but because it is cheap and easy, it can be safely recorded. While luminol is better, it has also inconvenients: it is rather difficult to use and what happens if it goes wrong? Like if the photographies are not good enough or if the preparation is bad. Better have a cheap and safe second test, so you still have evidence in any event.
But aftr all, still this question is irrelevant.
I realize that you tried to answer 12. Please try harder.
There is no need to. It's already obvious.
