I have a possible theory- my opinion only. Maybe-
KS Group ALL returns to the apt. for a after party or whatever, and the dogs get riled up- maybe the dogs are taken out and the noise/activity infuriates the neighbor, who KS argues with outside.
Police come soon after 1st 911 call, that was made by whomever heard the arguing.
Police send each party to their respective apt, warn to calm down.
(we do not know if police actually see or speak to anyone else that could have been at KS apt. during that time....nor do we know if police notated if KS car was there or any other guest car)
KS returns to apt, still riled up and the group decides to leave and take it else where, since there is a 'nosy' neighbor.
They leave- whether in one or 2 cars unknown.
(we still do not know if KS drove to Hardware or rode with others)
At any rate, the group leaves the apt. rather noisily, thumping and bumping down the stairs, which bothers a neighbor again and a 2nd 911 is placed.
20 minutes pass before police arrive back.... by that time all is quiet...neighbor may have gone to sleep or figured it was quiet now, oh well. Again , do not specifically know if vehicles were notated or doors knocked on - how police actually responded.
Police do not see or hear anything out of place and leave.
Group goes elsewhere and in the ensuing time, KS meets with harm, whether accidental or intentional.
Her vehicle and maybe some personal items if she did indeed take them(purse, phone etc) are stealthily returned to her apt in the wee hours by someone, who then leaves the premise. The scene then appears that it looks like that was the last place she was....and whomever winds up at a store.....
The same type scenario could be played out by one person and KS.
That is why I asked about roofies, et al. I am only speculating and do not mean it as a personal attack towards her, but maybe KS was pretty well intoxicated that night.
And maybe at some point , close to arriving home, or afterwards, KS inadvertently ingested a drug, unbeknownst to her. Maybe her actions that night were totally out of character for her and because of alcohol/drug use, she wasn't thinking very responsibly.
Only a theory, maybe there are holes, I dunno.
She is out there somewhere.