Hi,
I've worked with snapping turtles for many years, in NY in the wild and in zoo collections. In NY, eggs usually hatch in August; in points north, they sometimes hatch but remain in the nest until spring, when they emerge. Females cover the nest very well, unless disturbed in the process, and it's almost impossible to see any evidence of it once completed. Nesting is almost always in early June. They will travel quite far from water to nest sometimes, and if there is one turtle in the pond there are likely others; males are territorial but females are not. Upon hatching, youngsters head for water...you may have found stranglers, or early hatchers, or their may have been others under leaves, etc.
Here's an article I wrote on snapper natural history, with photos of a 50-60 lb male and of a 205 pound alligator snapper (related species) I cared for at the Bx Zoo: The Snapping Turtle, Chelydra serpentina
Enjoy,
Best regards, Frank