Princes in the Tower "the murther of his nephews towards the world", indicating that the boys did indeed meet their end during Richard's days. It is also unlikely that the princes would have been kept alive in secret by Richard for 2 years after their last sighting while rumours of his responsibility for their murder circulated. Some writers have also accused John Howard, 1st Duke of Norfolk; Margaret Beaufort, Henry VII's mother; and Jane Shore (Edward IV's mistress). Pollard writes of these theories: "None deserve serious consideration. The problem with all these accusations is that they beg the question of access to the Tower
Princes in the Tower current historians, including David Starkey, Michael Hicks, Helen Castor and A. J. Pollard regard Richard himself as the most likely culprit. There was no formal accusation against Richard III on the matter; the Bill of Attainder brought by Henry VII made no definitive mention of the Princes in the Tower, but it did accuse Richard of "the unnatural, mischievous and great perjuries, treasons, homicides and murders, in shedding of infant's blood, with many other wrongs, odious offences and abominations against God and man". The "shedding of infant's blood" may be an accusation of the Princes' murder. Hicks speculated that it