Keatsol, I did the open interview and even though Duke says 'business casual', everyone, with one exception, was in business attire. One dude showed up in khakis, loafers w/ no socks, opened dress shirt, and a blazer. Though he was looking "fly", he was certainly the elephant in the room. I would play it safe and plan on business attire and then shed the tie and/or jacket if you feel overdressed. But i wouldn't be surprised if everyone is decked out in full suits.