If a teller follows procedures should they have any accountability if the item is returned?
Not a terrific answer, but it's going to depend - was there anything obvious about the check that they should have caught - stale date, no routing number, etc - Following one procedure should not absolve an employees from following other procedures. Hopefully you have a training or procedure manual that goes over ALL of the conditions that should be reviewed when accepting items for negotiating - if ANY of those conditions are not met resulting in the item being returned, then of course - some accountability should be required.
Further, I have always recommended that managers walk the teller line - reivew transactions in work bins - if there's time - ask the teller some questions about a transaction - see if it meets your FI's procedures/requirements. Let them know that you're there to help, to coach ... and the more subtle hint is that you're watching.
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My comments are absolutely no reflection of, nor influenced by, my employer - take them at your own risk.