I’m not a rabid believer one way or another, but I am aware of the power that kings and other members of the nobility had 500 years ago-and it was pretty much absolute-not something I would have liked to see.
They most definitely could send someone out of the country, and have them held there in conditions as cushy or as wretched as the noble sender/abductor was willing to send payment for. There are even a few documented cases of noble kids and adults whose relatives paid to have them abducted and sequestered in the American and other British colonies as late as the mid 17th century. It took decades before they were seen or heard from again, and some of them didn’t survive the experience-which I’m pretty sure was the intent...
There is no proof one way or the other of who killed the sons of Edward, or if that is what happened, just clues, innuendo and bits of evidence on both sides for both opinions. I simply don’t think killing the kids made sense when they could be made to disappear for as long as he wanted while among the living, especially when Richard had so many other problems.
The problem is when they disappeared. For hundreds of years, the Ricardians falsely claimed that they didn't disappear until Henry VII became king. When Mancini's diary came to light in the late 1930's, the self-serving claims of Ricardians that the date of their disappearance was never firmly established during Richard's reign were demolished once and for all.
Contemporaneous accounts of their disappearance -- and much more importantly, the public knowledge of the fact of their disappearance -- lead to only one conclusion: they disappeared when Richard was King. The countryside was against Richard, and not just the Tudors, as Ricardians like to claim. The disappearance was one of Richard's problems among his countrymen. He could easily have made that problem go away... but only if his nephews were still alive.