Some observations/questions answered based on the search warrants, in no particular order...
The search warrants and case notes (
http://s3.documentcloud.org/documents/1283962/hedgepeth-case-files.pdf) shed a little light on this. What led investigators to JB is definitely very interesting and starts on p. 109. First of all, when they downloaded cell tower activity from the one near KR & FH's apartment, they found a call from his phone at 4:15 AM. They note that KR was picked up by his roommate just fourteen minutes later and that he might have known that FH was alone. Second, a couple years before FH's murder, in 2010, police from his home state called Chapel Hill police to say that he had made threatening comments and his parents were concerned that he was heading for Chapel Hill with a gun. Just prior to that, he had reportedly had some mental health issues and had sent a text to his mother that he was going to shoot her boyfriend in the head. If I'm reading the notes correctly (the names are blanked out, but it lists his home town), he was also at The Thrill that night. When asked, he refused to give a DNA sample.
According to the search warrants, a friend of KR and FH's told investigators that BE and KR (not FH) had had a physical relationship.
Webthrush said upthread
According to the search warrants (p. 48), the short calls from KR's phone were actual calls (33, 38, 37 and 36 seconds). The search warrant blanks out the name of the person she was calling, but the warrant that that information appears in is a warrant to search the car of the guy who spent the previous night on their couch (who I think is also the one KR had had a physical relationship with).
It seems from the search warrant that FH's phone was found and seized by police (p. 60), unless the purple HTC (?) phone was KR's.
One thing that's interesting about the 911 call, is that KR refers to the bedroom as "my bedroom", which implies to me that she considered the apartment hers and Faith's presence there temporary.
Another thing that's interesting is that the information about KR's ex's threats against FH came from another friend (not KR) (p. 87).