sentences:  A member of the "Group of Four", he was imprisoned from 1997 to 2002 after co-authoring a paper calling for democratic reforms.Roca is the son of Blas Roca Calderio, one of the founders of the Communist Party of Cuba.In 1961, at the age of 18, he was among the first batch of a young elite selected for training as fighter pilots in the Soviet Union.