The DNA was 'touch' as in transferable DNA and there are some irregularities as to how it was matched to Kohberger. Kind of odd there was none on the actual sheath itself if it was his. It was only found on the press stud which is an obvious place to find DNA..
He didn't follow any of them on SM. The police stated they could find no physical or online connection to any of the housemates. You can easily check this by googling. They said this at the press conference after his sentencing.
He had ASD, and also OCD, and had obsessions about germs and washing his hands. I wear disposable gloves (you can get boxes of 100 for a few £ on Amazon), when taking rubbish out and cleaning out my car. Many people do when doing dirty jobs.
I believe the sighting you are referring to was when he went home for Christmas break SIX WEEKS after the murders. I kind of think he would have logically disposed of any evidence a while before then! The interior of his car was disassembled btw, and no a trace of DNA, blood or a single hair was found from the victims or the house. This was the vehicle he jumped into straight after stabbing 4 people an accumulated 150+ times and sped off in.
He had also done a cross country trip home with his Dad in the car so you would assume there was rubbish to be disposed of. His parents may have asked their neighbours if they could put rubbish in their bins if theirs were full after Christmas.
The reason he took a plea deal was due to the prosecution repeatedly delaying the defence having access to evidence, the Judge denying legitimate legal motions, which would have meant he had no way of a fair trial in addition to his guilt already being determined by media and public. This was a death penalty case. His mother was also publicly opposed the death penalty years before the murder and his parents and sisters were very involved in his defence.
He's now filed an appeal to vacate his plea and asking for a new trial which will be death penalty as well, saying he was misadvised by his defence and coerced into taking the plea deal to avoid the death penalty by firing squad. This has probably come about due to evidence he hadn't even seen being released to the public.
This case stinks to high heaven and the victims deserve justice IMO.