I can't think of a better place for a gun to be stored than in a bank safe deposit box. If local law prohibits carrying a firearm into the bank I don't have a problem with confronting this customer over that fact. He is the one that opened the box in a non-private area. We don't know the contents until he shows us. In this case he breached the privacy.
If this guy's wife gets shot and he was in the box the day before the shooting would I tell the police he has a gun in his box? That's a tough one. If you do tell the police and he's investigated because of that but the real killer shows up this guy is going to be quite perturbed and will likely sue over the breach of privacy contract we've all provided our customers. The bank would probably lose. On the other hand, if it turns out that is the one piece of info needed to send the guy away for life, I can't see any judge in the land finding fault with the bank for helping solve the crime. Hopefully the local cops think of subpoenaing bank records since the spouse is always the first suspect. Then you have the cover you need to spill your guts on what you know about the safe deposit box.
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Sponge Steve, CRCM, CBA
Opinions expressed are mine and not my employer's