sentences:  Amnesty International declared the four prisoners of conscience, "detained solely for peacefully exercising their rights to freedom of expression and association", and called for their immediate release.Roque, Bonne and Gómez were released in May 2000, but Roca was held for an additional two years.The Human Rights Committee of the US National Academy of Sciences speculated that he was "singled out for particularly severe treatment because he had been a member of the Cuban Communist Party and his father had been one of its founding members".