The culprit would have to go through a lot of work to push him down the shaft, stab him, and manage to make it back up considering the elevator doesn't move. Unless this is another case like last week, only one person on the suspect list could really pull that off.

[ She motions toward Beat, wether he's paying attention or not. ]

Unless he was stabbed first, pushed second, but there would be blood around the elevator entrance and not just on his desk.