Thus, the speculation of You Mingxu and Xu Mengshan about the killer's method of entry was confirmed—
The killer must have entered at half-past two in the early morning, following the victim into the room and subduing her with a neuro-paralytic drug.
He must have stayed at the scene for at least two hours.
Xu Mengshan immediately arranged to focus on the surveillance footage around the area between half-past two and four to six in the morning.
However, the building was in a remote location, somewhat outdated, with fewer surveillance cameras. There were many alleys and blind spots that the cameras couldn't reach. So far, nothing has been found.
