A Piraeus court has acquitted seven state doctors of manslaughter in the prison hospital death of a dangerous criminal five years ago, in a decision made public yesterday. The misdemeanors court ruled that the Korydallos Prison doctor and his six colleagues from the Nikaia General State Hospital could not be held responsible for the September 26, 1998, death of Sorin Matei, 26, who choked to death in his bed where he had been left lying, bound hand and foot and heavily sedated. Matei, a Greek-Romanian robber, died three days after being hospitalized for wounds received during a botched police operation to rescue a family he was holding hostage in their Athens flat. One person died. He had embarrassed police earlier that month by escaping after another highly publicized hostage-taking venture covered live on television. During his arrest, he suffered severe head injuries.