Snips by me and BBM
Thanks CATABD, I've snipped parts of your post above.
A light on or seeing a car - has been my primary thought from the first time I heard NH's account about KB returning to the apt. If (meaning IF NH's account is truth), his account of the "spooked" remark seems to support that theory. He used the word spooked; I do not believe he would have used that word if KB seemed afraid.
If NH fabricated the account of the "spooked", I would pretty much jump down off this fence and believe him to be responsible KB went missing.
From my memory it was indeed NH that described the ride home and used the term spooked.
Fly little butterfies and find Kelli.
Thank you JustyThougts for taking the time to read and respond to my post! And, thank you for clearing some things up for me! 
Im leaning towards the idea that NH did not fabricate Kelli being spooked. I am wondering if he interpreted her reaction to something she saw, and thus described her reaction as spooked. Again, I know this sounds as if I am l mincing words, but it may be important to have an accurate description of what may have been Kellis feelings or thoughts at the critical moment. I looked in the dictionary, spooked has several meanings; I am only concerned with two that are relevant here:
To startle and cause nervous activity in; frighten.
To become frightened and nervous.
If we take the literal term, and we must because NH has given this description, than, NH is describing a person who is frightened.
Now, this puts me back to my original idea, why would she get out of the safety of a car to go where she felt spooked or frightened? That doesnt make sense. Perhaps NH doesnt understand or recognize some of the subtle nuances of behavior?
Just my thoughts