The unidentified male had a line of sight to Cheri Jo Bates' Volkswagen Beetle parked on Terracina Drive, he was standing in the alleyway 30 minutes subsequent to the library closing its doors, and was the last person seen in the alleyway prior to screams being heard, approximately 45-60 minutes later by local residents. This is the most viable suspect in relation to the murder.
We know Cheri Jo Bates was not present in the library at 9.00 pm, and did not leave at closing time. If this was her murderer, he may have been under the impression Cheri Jo Bates was in the library when he arrived to the Riverside campus. He disabled her vehicle and waited for her to exit. By 9.30 pm he would have realized she hadn't exited the library, but with her vehicle close by knew she would be returning sooner rather than later, and the alleyway was the perfect vantage point.
If this man was a random killer not familiar with Cheri Jo Bates, simply on the lookout for lone women, he certainly rejected the opportunity that presented itself at 9.30 pm when a young female student passed him in the alleyway. Does this, along with the disabling of Cheri Jo Bates' vehicle indicate he had a specific target in mind? It definitely points in this direction.
The DNA comparison ruled out 'Bob Barnett', but how many of Cheri Jo Bates' colleagues, companions and friends of the day have latterly been screened and been eliminated or otherwise.
This crime has all the hallmarks of a killer who knew Cheri Jo Bates, knew where she was going that evening, knew her vehicle - and if the man in the alleyway was our killer, he was prepared to wait a substantial period of time to secure his objective. The answer to how close this person was to Cheri Jo Bates may lie in the discarded cigarette butt, how long he was prepared to lie in wait in the alleyway, and possibly his mistaken belief that Cheri Jo Bates was studying in the library until closing time. These, coupled with the disabling of the Volkswagen Beetle may point to the inner circle rather than a stranger.