They may have been wasted, but we still don't know how Duncan knew this family? And how did his association with them slip through the cracks?
Obviously he was new to the area so that explains how the association slipped thru (just not known)...and like you, I'm very curious about how he knew the family. Maybe thru drugs? And, there was quite a lot of speculation that the murders could have been random & committed by someone passing thru...the house is real close to an Interstate. So it's possible that there wasn't an association? What is weird is that he didn't keep moving.
sw
The sheriff repeatedly states that the crime scene was highly emotional, that the drug use of the adults killed was only recreational, and that no family member or friend was ever seriously considered as a suspect.
There was also speculation that they knew this guy and he had been at the party the night they had it.