Richard's nephews (spoiler).

I thought he would have staged their deaths to look more like accidents instead of just having them murdered outright. He was normally so clever about staging everything else. I guess it didn't matter at that point since they were the last two left between him and the throne. It just seems strange though, since he must have known that killing the boys in so obvious a manner would be the last straw that finally turned the majority of his remaining supporters against him.

"The storm cannot be stopped, but it can be survived.'"