It's possible it was two unrelated guys trying to decide what to do or who to ask for help.
I don't believe the "somebody better help" guy would have been the killer because there are enough other exits out of there that the killer could have gotten out without talking to anyone.
And why would anyone necessarily associate a guy walking by that aisle with her, anyway? It may have been minutes or hours until someone else wandered past and saw her. Even in the time it would have taken to get to someone and call for help, the killer could have been long gone without passing by the circulation desk.
The facts take me to the points I've already mentioned in other threads. Now, I will speculate a bit since we've placed a somewhat prepared killer in the environment of his choosing. In my theory I'll omit certain factors such as . . .
1. Level of experience of killer (i.e., killed before or not).
2. Alternate intentions (i.e., to fondle, flash, etc.).
3. Whether he was a student or not.
4. What he did later (i.e., additional crimes, taunting, etc.).
I am trying to make an "educated guess" based upon the framework of facts, and draw logical conclusions. I don't think the information we have at the moment will shed much light upon points #1 through #4 above.
Here goes . . .
The killer has a strong desire to commit a crime against a female. It is very likely sexually motivated, in some sense, and violent as well. He has thought about this and the more he does, the more "build up" occurs. The setting of his choosing is perfect, as it allows for him the type of victim of his choosing (i.e., young, attractive female) as well as a degree of risk (i.e., setting) without too much risk of being caught (i.e., holiday and secluded area). He goes prepared with his hidden pocket knife to watch for potential victims of his liking. It may or may not have been the first day he went there, as he probably may have needed to build up courage, may not have seen someone that "clicked in his head", or he determined on a given day that it was too risky.
The killer either saw Betsy elsewhere in the library and followed her into the core, or he was already waiting there (or nearby) when he saw her. I'd guess the latter, since spotting and following someone may never lead him to that secluded area of his choosing.
The Dean walks by at 4:30 p.m. and sees 2 guys "skulking about" and Betsy is nearby. He is busy, by his own admission, so he probably only glanced and didn't have much reason to "take it all in" so-to-speak. Meaning, he may not have noticed the true killer nearby.
If the killer was in the core or nearby, he was already aware of the two males, so he took precautions not to be seen by them too much if at all. He avoided them by moving down aisles and kept an eye on them through the open shelves as best he could. When the moment presented itself, he approached Besty from the front and stabbed her once in the chest sometime between 4:35 and 4:45 p.m.
She never reacted or screamed because she had no reason to fear anyone approaching her in the library. Who would? The shock of the stab prevented her from crying out, but her fall knocked books down and made a noise.
Regardless of his intentions, the killer flees upon hearing all the books come crashing down because he is also aware that the two males were in that area. He slips out unseen.
The two males see Betsy lying near a pile of books on her side, and for whatever reason, they choose to do nothing more than tell that girl "somebody better help that girl" before leaving the core. They either leave and do nothing, or actually tell someone else before they leave.
Why were they there? Who knows? It could be innocent, or it could be they were hesitant to come forward due to the fact one - or both - were engaged in some homosexual activity at some point that afternoon in that area. It was known to occur in that area, but I do not think it had anything to do with why Besty was murdered.
Thoughts?