In my opinion, the killer was more than likely covered head to toe in clothing. Coat, gloves, and most likely a mask. Even if this was a heat of the moment situation, and not planned out at all, most people would think to at least throw on a pair of gloves and a mask before they head out the door to kill someone with a knife, let alone 4 people. Everyone is aware of fingerprints, DNA, and cameras. I doubt there is DNA from the killer under the fingernails of any of the victims. I think if they used a Kabar knife, they did not cut themselves and leave blood either.

What if the person had a stray hair or something from a family member, roomate, their own head, or even a pet, stuck to their glove/mask/coat/shoe that became dislodged during the attack and left on the blankets or floor or wherever somewhere in the house.

Let’s say it’s a serial killer that lives with granny dahmer style, maybe they found 82 year old granny’s single hair strand on a blanket, and they match her dna to it, obviously it’s not her, but maybe it’s her 50 year old son that lives under the same roof and has been fantasizing about this his whole life. LE was likely on hands and knees combing through every square foot, looking for anything and everything. I think there is a 85% chance some form of DNA was left behind, and if that’s the case, LE will solve this. Just a matter of how long it takes.