How's This for a Mysterious Setting?

Talk about a great setting for a mystery! We recently visited the Graue Mill in Oakbrook, Illinois--a historic waterwheel grist mill and museum. My historical mystery writing friends would love this place; it's thought to have been a stop on the Underground Railroad, and there is a museum in the basement which is a tribute to the abolitionist movement. We got to see demonstrations of how flax and sheep's wool are spun into yarn (with old-fashioned spinning wheels); how yarn is woven on a loom; and how corn and other grist is made into meal.
The mill is located on Salt Creek in this idyllic setting; we were able to observe both the giant waterwheel and the water rushing over a nearby dam. But here's the potentially sinister part:
These ducks apparently thought that we had bread crumbs. They came boldly up to us, a gleam in their beady eyes. As luck would have it, we had brought a picnic, and a certain youngest son never finishes his food. However, the moment a crumb was produced, this happened:
Accomplices came marching over the hill in alarming numbers! I always knew those ducks worked in gangs. They chased the boys around a little after the crumbs were gone, but no actual crime was committed. THIS TIME.
Anyway, back to the mill. It was a lovely day: only in the seventies, which is where it should be, and feasts for the eyes wherever one looked. The mill itself would be worth the journey even if one never went inside. It's a noble old building, full of history, and a real pleasure to see.

But what about the mill as a setting for a crime? Any ideas? After Suzanne Adair's ghost story, I was looking over my shoulder during our whole visit, and Graham was sure he would fall through the creaky old floors, which he figured, after nearly 200 years, were just about ready to break. So perhaps we all felt it, that potential for mystery in this setting.

More later . . .