Bai Yi was aware of Gu Xin's suspicions. The murderer must have sneaked into the victim's courtyard through the Lotus pond and then left through the Lotus pond.
Last night, the few of them went to bed late. He and second white even went to check on a few people. They also went to bed at dawn.
The Bai family didn't know martial arts. He and second white definitely didn't make any noise. So how did the murderer know when they were there and when they weren't?
Bai Yi was sure that no one had been in the Bai family's courtyards before dawn, so the murderer did it after dawn.
Diving into the water, killing, setting up the scene, leaving, and finally returning to his room, it didn't seem like something that someone without Kung Fu could do in two hours.
