Are you sure there aren't any in the murder room? There are quite few prints in the room too partial or/and smeared to match. Any of those could be from Amanda and Raffaele. And also, since it is only the right foot that prints are assigned to, it would appear that each only got one foot covered in blood. I think the simple answer is they hopped to the bathroom to clean up.
No, they couldn't be from Raffaele and Amanda unless they were wearing Rudy's shoes. Not even Massei bought the smeared print being Amanda's and he was
looking for ways to put them in there.
No, presumptive blood tests cannot be used to eliminate the presence of blood, only a confirmatory blood test can do that. Obviously though, if no presumptive test detects blood nobody is going to perform a confirmatory test since the presence of blood is not indicated. Presumptive tests are for indication, not elimination. One certainly cannot use a negative TMB test to eliminate a positive luminol test. That is simply because TMB is not as sensitive as luminol and therefore luminol can detect samples that TMB can not.
*sigh*
One more time before I have to go, using real words this time. Blood has cute little things in it that react to these tests. All these tests are used because they will find those cute little things and celebrate with them, by lighting up, turning colors, get fuzzy, crystallize--lots of ways to party! There's no point to having a blood test that doesn't find the cute little things and party with them--think about it! If they don't party, they're not cute--uncool you might say. You know to stay away.
However, some of these tests are kinda...non particular....about who they party with. A little
promiscuous you might say. They'll party with cute little things in other substances besides blood. That doesn't help. Luminol allows you cover the whole room, but is kinda...
easy...I suppose that makes sense as much as it gets around, it parties with a lot of cute things from all over that aren't blood. Thus a lot of institutions, like ILE and the FBI, will use TMB to double check before they take them home, they don't want mom to get the wrong idea I suppose. So they give TMB a try, and if it finds cute things to party with you know that you probably have blood. Still you have to bring it home and see if mom confirms. Mom always knows it's blood, she just doesn't leave the house and go out looking for cute things, you can guess why.
Get that? You get a positive with Luminol and a positive with TMB and odds are it's worth confirming. If you get a negative with either it's not blood, there's nothing 'cute' about it no matter what you thought at first--uncool to the max. That negative test on either
eliminates that it has the properties of blood, whichever one the test you employ is using to look, something blood always has so you know it when you find it, unfortunately other things will have it too. The confirming test is only for human blood, and usually requires lab conditions.
Confirming the presence of blood was not their priority, extracting DNA profiles was and they needed all the samples for that.
They weren't blood, that's why they didn't confirm them, they just tried to think up excuses why they might be. They didn't find DNA either, at least for the vast majority, which means the one they did find DNA in was highly likely not inherent to the splotch, but the floor, or what the splotch attracted, being as it might well have been a sticky spill or somesuch.
Oh, you saw my reply. Indeed, you replied...but as I recall it, it was to suddenly change the subject and come at me with a different talking point.
Maybe it was mercy, Fulcanelli. I'm right about this, think about it.