Interesting that you snipped out my following comment that BOTH Raf on the clasp and Meredith on the blade make the likelihood of contamination less likely to me. The fact that two highly unlikely events is strange to me, unless there is a wider conspiracy.
I snipped it because both these claims are false. The clasp can't be evidence unless we know what happened to it between the day the police saw it and the day they collected it. We don't.
C/V admitted Meredith was on the blade, only argued that is wasn't reliable.
Wait, if it wasn't reliable, it wasn't reliable. It's not evidence. And what happened when the SC asked for a re-test on the knife? They found nothing indicating that it had ever touched Meredith. That was just last November.
I'll admit to disappointment that the bra clasp wasn't collected in a more timely fashion, but it was a closed crime scene. Very few people were allowed in and out.
But somebody touched it, right? It moved a yard across the room. It ended up under a rug. So the issue isn't the timing, or the number of people who were allowed in and out, it's that the thing was compromised. It had evidentiary value on the day after the murder, but that was lost because it wasn't secured.
It's certainly "possible" that Raf's DNA was transferred to the clasp. But highly unlikely, and therefore reasonable doubt is not met. Not to mention, countless cases have been solved in recent years with DNA evidence decades old.
The point is that no one has any way of knowing how unlikely or likely contamination might have been; that's why the clasp can't be evidence. If you're going to hang a whole murder case on a man, you want the evidence against him to be clear and uncompromised. This clasp -- the only thing that ties RS to the murder -- was clearly compromised, because at least one person touched it or it could not have moved across the room and made its way under a rug.
If decades had passed and the thing was exactly where it had last been seen, your point about countless cases would be relevant. But it wasn't decades, and it did move across the room, so no dice.
You don't want to argue about evidence, but you mention the only two bits of supposed forensic evidence against AK and RS. Both of them -- separately -- have been shown to be bogus.
No Kercher DNA or blood on the knife. Not the murder weapon.
No chain of custody on the clasp. No way to know how any of the DNA got on it.
No evidence, no motive, not guilty.