A judge on Friday convicted and sentenced to life in prison three members of the Red Brigades terrorist group for the 1999 killing of a government labor adviser, court officials said. A fourth was convicted and sentenced to nine years. Prosecutors had asked for life terms for all four, who were accused of gunning down Massimo D'Antona in Rome in May 1999 while he was working on labor market reforms that were bitterly contested by Italy's labor unions. Sentenced to life terms were Nadia Desdemona Lioce, Marco Mezzasalma and Roberto Morandi. Paolo Broccatelli received a nine-year term. There was no explanation for the ruling; Italian judges provide written explanations of their verdicts several weeks after they are issued. Several other defendants on trial were given lesser sentences.