Security Guard or Staff?

This post is an opinion rather than a list pictures. My friend invited me to his apartment today and his building has a security camera that points directly to the front lobby, but similar to the Cecil you can hide at the corner without being seen by the camera. For 'role play' purposes, I experimented 'hiding' at that spot, but was unsure whether I can be seen. The only way I can be sure is to check the camera logs. Thus, I'm sure the murderer had to do the same and had access to the cameras before hand. Additionally, to access the roof, and lockout the elevator, you would need special keys only staff or security would have.