This, from Wiki about Edward of Warwick:
After King Richard's death in 1485, Warwick, only ten years old, was kept as prisoner in the Tower of London by Henry VII. His claim, albeit tarnished, remained a potential threat to Henry, particularly after the appearance of the pretender Lambert Simnel in 1487. In 1490, he was confirmed in his title of Earl of Warwick despite his father's attainder (his claim to the earldom of Warwick being through his mother). But he remained a prisoner until 1499, when the pretender Perkin Warbeck appeared. A plot between Warwick and Warbeck for Warwick's escape was alleged.
On 21 November 1499, Warwick appeared at Westminster for a trial before his peers, presided over by John de Vere, Earl of Oxford. He pleaded guilty. A week later, Warwick was beheaded for treason on Tower Hill. Henry VII paid for his body and head to be taken for Bisham Abbey in Berkshire for burial.[6] It was thought at the time that Warwick was executed in response to pressure from Ferdinand II of Aragon and Isabella I of Castile, whose daughter, Catherine of Aragon, was to marry Henry's heir, Arthur. Catherine was said to feel very guilty about Warwick's death, and that her trials in later life were punishment for it.[7]
A number of historians have claimed that Warwick was mentally retarded. As Hazel Pierce points out, however, this surmise is based entirely on a statement by the chronicler Edward Hall that Warwick had been kept imprisoned for so long "out of all company of men, and sight of beasts, in so much that he could not discern a Goose from a Capon."[8] It seems likely that Hall simply meant that long imprisonment had made Warwick naive and unworldly.
Upon Warwick's death, the House of Plantagenet became extinct in the legitimate male line.