Richard III has really gotten a bad rep. A lot of people judge him by the Shakespeare play, even though said play was written a century after his death.
If you hauled Richard III into a modern court room and charged him with the crime of murdering the two Princes In The Tower, the case would be quickly thrown out. All the evidence against Richard would be hearsay, there would be no witnesses for the prosecution to question, and the case falls apart.
Some think Henry Tudor, who took the Crown after beating Richard at Botworth, killed them. Motive, to solidify his hold on the Crown, the Princes would have had a stronger claim than he would.
Of course, this is all theory, but when you break it down Henry is just as easily guilty.
I wonder if they'll ever do a DNA test on those bones that are thought to be the two Princes (which were found about a century or so after Richard's time).