That is interesting.
I read it as state of a deteriorating mental condition affecting physical dexterity.
(she got worse as the day went on kinda thing...)
One might almost suppose that she might be running on no sleep, as well. Adrenalin eventually crashes.
I figure they luminol'ed everything on the second trip to the house, and again after the bloody tool remark by LS. Typically, its best to really photograph/video the crime scene before putting chemicals all over. Luminol doesn't tell whether something is human blood, a swab test and a simple reactive test is used.
If it turns out that test shows human blood, then blood spatter analysis begins, along with DNA testing. The garage may have been an early focus if LS is telling the truth, but eventually, I'm guessing there was lots of luminol and. probably RSID testing If no RSID testing, I'd get someone out there to do that.
Then the various teams meet, submit their info, and the lead investigators put it all up on a nifty map of the premises. Even if the only goal is to check out whether LS was truthful about the garage blood, this exercise will tell a story. If the story points to any sort of abuse or criminal behavior, then there can be probable cause to bring a person in for questioning, with their lawyer, because charges are looming. If the person cannot explain what the evidence shows (or refuses to), that's duly noted.
I don't think they are interested in using all of this as an LS lie detector though, as it's obvious she has done some lying. I'm guessing that the story told by the already-collected evidence (by now including fast track DNA, almost certainly) is a story that warrants the collection of more evidence or perhaps close up pictures of the crime scene.
Consider that in the EARONS case, if the VCSO's CSI's had not collected more than enough samples of DeAngelo's DNA and kept it closely guarded in their freezer, the tests that were run years later would not have been possible. In this case, would likely be blood evidence. There's almost always something new in the forensic story that investigators didn't truly expect, when all that evidence is looked at through a DNA lens.
OTOH, perhaps they found something up north in the previous days and that warranted a trip to the house.
I can think of a few other things they could be looking for, that may not have crossed their minds early on but, after review by a team of people, now warrants a closer look at certain parts of the property.