Stairs.
You dash up the stairs as quickly as you can, but come to a standstill the moment you hear the elevator door opening. A moment later light comes from the bottom of the stairs.
"Hello? Anybody there?"
Male human. Probably the guard. You have to wonder why humans do that. Do people ever come out of hiding if you ask politely?
You slowly advance upwards, being careful not to make any noise, until you reach the top of the stairs. You listen carefully for a second and then press the button that opens the door. The area looks clear. You go through and close the door behind you.
You find yourself in the reception area of the glass tower. There's not much here. Just the elevator, the reception desk (hiding a computer console behind it), the guard's datapad that was left behind in his rush to investigate, a small waiting area with places to sit, a door leading to a tiny refresher and another door leading to a tiny kitchen. You notice that the waiting area is decorated with glass things similar to the little glass bird you found on the victim, but also quite different. The bird looks almost real, like a real living creature was turned to glass. These glass things on the other hand... The curves look organic and visually appealing but they don't appear to be depicting any definite creature, at least not with a great level of realism. Still, they look shiny, maybe you could sell them for a few credits. There's also two locked doors next to the stairway, both of them requiring a keycard to open. One presumably leads outside, while the other says "Emergency Exit, keep clear". If you had to guess, you'd say it leads upstairs.
The smells here are somewhat more interesting. There's the scent of the Killer spread around the waiting area and the elevators, confirming the fact he goes in here frequently. There's also the scent of the guard that was here a while ago spread all over this place. The victim's scent is leading to the elevator and the door that says Emergency Exit, though it's much fainter. There's also other faint smells, both human and non-human, but they are even more faint than that of the victim. Your guess is that other people come here, but not often.