[oceanview]

but the finding of the corpses most likely led to sweeps and searches of the area, so how does that help them?

[Domestic Church]

"but the finding of the corpses most likely led to sweeps and searches of the area"

Most likely? And how thorough a sweep will they do under ice? And how far a sweep will they do? The bedrock certainly has plenty of iron ore to throw off metal detectors and any nuke device surely would be lead lined. And it might not be a nuke. The river silt will cover anything quickly. We don't know how far the body traveled down river or how long it was under ice before being found.