As I recall, Zhou Yang had invited Zhang Bing to check out his microblog that night. When Zhang Bing died, we couldn't find his cell phone which had obviously been taken away by the murderer!

Perhaps the murderer was inspired or triggered after reading Zhou Yang’s post and decided to kill everyone on the ghost bus that night. The first people he located were the hostesses of the nightclub. Zhang Bing must have kept their information on his cell phone so he contacted them using Zhang Bing's phone.

At the time, I assumed the murderer stole one of the hostess' cell phones out of greed but now it seemed he had another reason. There must have been chat records that he didn’t want the police to find. 

Then, the next easiest thing was to locate Zhou Yang. The murderer...