You're supposing the attack on Wolf was the staff's work. There's no doubt Von Karma was murdered by the staff, given where the body was found, but we should also consider Kei acted by his own will, for one reason or another.

[However...]

If Kei was part of the staff, it's possible von Karma was murdered because the attempt to kill Wolf failed.

[Hey, Bigby, over here. Dojima turns his head towards Bigby. Would you be as kind as to provide your witness testimony?]

Wolf, do you remember anything? How you got woken up at a time everyone but staff was knocked out, for example? I'm not saying you're staff, but it's certainly a deviation from normal and could give an idea what the victims do or see before they get murdered.