Bo rescued her and while filming location scenes at Duke University, Sarah realized Neil was indeed the killer, so Neil stopped Sarah from escaping and chloroformed her as she cried out for Bo. He then dragged her to the University clock tower where he held Sarah captive.
Bo rescued her during filming at Duke University; while filming, Sarah noticed that Neil was the murderer. Consequently, Neil prevented her from escaping by using chloroform and holding her captive on the university clock tower.