Sorry to be a bother again but am trying to recall a case. I recall that two young men, hitch-hikers I believe, entered a store (or gas station, or restaurant), and were asking for the police to be called. They were frightened of the person that had given them a ride there. They refused to leave and may have eventually called 911 themselves. Any ideas?

Sounds like the Bill Henderson murder

http://unsolvedmysteries.wikia.com/wiki/Bill_Henderson