Who would be liable for a customers death in an armed robbery because the employee refused to give over money, the robber or the employee?

You need a mentor. I'll humor you as briefly as possible. We know the felony murder rule tells us that the robber thusly convicted is responsible beyond a reasonable doubt in a criminal capacity. Civil liability can follow at the lower evidentiary threshold for direct, vicarious, or concerted liability under a handful of theories. You're really asking if there is a way to hold the employee, and by proxy the employer, liable. There is a Plasgraf issue (248 N.Y. 339 (1928)), whether the bank employee owes a duty to customers to prevent injury or death during a robbery. Arguably, you can make a case either way. The second issue, assuming such a duty can be found, is whether the employee breached that duty of reasonable care. The existence or non-existence of one document, in particular, will be critical to both issues: written bank policies on cooperation with robbery demands. I'm no expert on the subject, but I've never heard any employer or law enforcement agency suggest anything than cooperation. Recent news stories have put employer stand-down policies front and center. Presumably, such a policy recognizes that non-cooperating can expose anyone on the premises to danger.  And a good secondary source of authority would be law enforcement and industry guidelines on the same topic. Bottom-line, there's no correct answer. Here's a secret that most law school students and graduate forget for approximately six years from the day of their first class: facts matter. Facts trump law because facts tell us which law to apply and which hedge to trim.  The facts of this hypothetical, as created by the professor, will give you one or more hooks to demonstrate your legal analysis. Spot the Palsgraf, identify the criminal versus civil standard, spot the employee liability versus employer-vicarious liability issue, and identify those facts which support either conclusion and take a position.