The volume of the disturbance in the apartment that triggered the second visit by LE (in my opinion) was Kortne being rendered unconscious or otherwise unable to fight back, or dispatched by suffocation, injection, etc.
Being rendered unconscious or or dispatched by injection of a controlled substance gives the actor some legal wiggle room as he/she can claim it was self inflicted if caught moving Kortne or her remains. I sort of like this scenario, however it would exclude the neighbor and the people she argued with at the bar. The spotlight would be on whomever was in the apartment with her. Without blood, the cleanup would be limited to putting disturbed items back in their place, but does eat up some of the available disposal time and distance to transport, and the actor would have to wait until he/she was sure that LE had left the area and that no one was out walking about/smoking/walking their dog/etc.