How long will this guessing game continue? Are you suggesting that each time you find a new set of irrelevant data that the investigators should test an entirely new hypothesis?
The investigators had found discarded debris outside in the yard, too, and briefly thought it was important. I believe it was something in the way of discarded syringes or pieces of fabric.
We know, too, that investigators returned to the cottage to collect more evidence than what was originally secured, including a guitar, a book, a hairdryer, and other items. In other words, they did what good detectives do.
But, you say, look at this other thing! This must be the real clue! This is the turtles-upon-turtles approach of the conspiracist. If the three DNA "clues" were relevant then they would be examined. As it is, going after these other "clues" does nothing to help Raffaele's legal defence. They are fully concerned about the abundant DNA left by their client and not by who was scratching each others' backs, swapping undergarments, or other similar guileless nonsense.