I was hoping the recent posts on this thread were because new information had appeared.
Re the butt-dial call, two thoughts. One is that, my understanding of how a butt-dial call happens, is that the number has to already be in your phone/contacts. That's the only way just a few random screen connections could make a call, I thought.
And yes I actually have stayed on the line listening for a few minutes when I received a butt-dialed call. But that is only because (see above) I knew who had butt-dialed me, because they were in my contact list.
Second thought is that if the caller was from the eastern US time zone, then the hour of the call is less automatically suspicious. I guess LE has spoken to the caller so they probably know whether the caller knew Derek or not.
Hoping Derek is found soon!