Trust

Originally Posted by wolf
He set his pistol on my desk and came back for it about a half hour later ...

It seems that you have either left something (EEI) out of this story, missed something when the event took place; or, the cop's name is Barney and he kept his one bullet with him in his shirt pocket!

Unless you have a special relationship with this cop and/or his department:

*Locking the pistol up in a monitored area [i.e. is the foyer monitored?] would have been a better option for both personnel safety and property security.

*The pistol should have been deactivated (e.g. ammo stored separately, magnetic key (ring worn) safety, magazine (removed) safety, trigger lock (handcuffs through trigger guard behind trigger) ... etc. regardless of where the pistol was stored.

*The cop should have gotten a receipt for the pistol from you (e.g. held your driver's license, your facility ID, annotated business card ... etc.).

The cop not taking his pistol back to the unit was fine; however, the limited information you provided makes it appear that the cop was trusting to the point of being irresponsible and some weapons security retraining is in order.