My main conclusion about this case is that 90% of the weird can be explained by everyone being blitzed out of their mind.
KR probably has a patchy AF memory of that night, but the only logical explanation is she hit him. Maybe he'd fallen or bent over, but she felt that bump. Perhaps she considered it, but couldn't see anything, was basically blackout anyway and it's was cold af out there so she didn't get out and check, dismissed it, went home and passed out. Or maybe she was mad and made a snap decision to leave him to his mates. Or maybe she meant to. Maybe she herself doesn't really know. I think she had an inkling in the morning though. Everything she did once she realised he wasn't home sounds like someone putting a blackout night together bit by bit and the panic and denial of someone with a dawning realisation of what might have happened.
JOK was also completely plastered, it might not have taken much force at all to put him out, when combined with the weather and the alcohol.mm Those weird scrapes could just have easily come from other drunken bangs and scrapes earlier in the night, or perhaps trying to get himself up. The cold, ice, head injury and blood alcohol could have put him under very quickly even if it wasn't immediately lethal. Then he's just about snow dusted lump on a dark night where nobody is lifting their head up if they can help it.
As for the party cops weird behaviour - They're cops, I don't think they killed him. I think they acted shady because they were up to *advertiser censored* that night that could get them fired. Drunk driving, coke, weed, something unrelated, but very important for them to hide. Probably didn't come outside to the police line because it was blatantly obvious to any beat cop what they were recovering from. Perhaps they were too busy bricking it about s murder case-level forensic sweep of their house when they had some naughty *advertiser censored* stashed inside, and may they did pull in a favour to skip that step.
Also, if they were leaving and driving while off their nut it would explain how they didn't see a thing as they left. A snow dusted dark lump off to the side would probably get a glance when you're bolting to from a warm house to a car in a blizzard.
The phone says stuff sounds very very technical and depend if on certain factors.
Any theory that isn't the very very benal drunken DV with tragic consequences requires god level conspiracies. Absolutely insane the amount of fans of this woman there are out there.