That is a thought. It might be that there was a 3d rooster that got killed right about the time the eggs hatched, but I don't think so. I'm pretty sure there was a true White Leghorn rooster, because my Roo's brothers are very white, with just a hint of Rhode Island Red and Barred Rock coloring in their feathers, or a speckling of Buff Orpington coloration on the heads of the white females. Are White Rocks pretty common? The farmer seemed certain he has White Leghorns. I don't think he has too many breeds, but he might not really know what he has, since he's not a chicken expert.
I will ask the farmer whether a dead 3d rooster is a possibility, and if so, what his breed is. I think he would have mentioned it, though, because he really got into telling me how all 5 of his Sebright Hens had died, full details.