The Fort Hood shootings led me to think again of this question.  Let's assume that something similar happened with a large private employer, say a military contractor; and let's assume that the murderer had killed non-employees, so worker's compensation laws wouldn't limit recovery against the employer.  Would the employer be potentially liable on a negligent supervision / retention theory if it appeared that its employee, who eventually shot many people at the contractor site, had expressed support for jihadist violence against Americans, and the employer did nothing to monitor or remove the employee?  Or would the contractor be immune, either on the theory that a person's political statements can't count in such situations, or perhaps on the theory that the plaintiffs couldn't shot but-for causation (perhaps because the employee could have equally committed the shootings even if he had been fired, since the contractor site wasn't limited-access)?

Eugene