Police
At least one policeman, likely several -- this is an obvious faction. Their primary objective is to piece together what happened, and why. (There should likely be some sort of external timing constraint: for instance, the commissioner will need to present a public report by the 6pm news, and he wants answers before then.)
They should be fairly divided politically, and have various ties to other characters. One might be, eg, married to one of the employees of the company. (Leading to the inevitable "get out -- you're not objective" arguments.)
