MEXICO . . . MURDERED LEADER'S BROTHER QUITS

Mexico's deputy attorney general today made sweeping accusations that his own boss and two of the country's most powerful officials conspired in the Sept. 28 assassination of his brother -- the ruling PRI party's reform-minded secretary-general. He then resigned from his post and the PRI. At an angry, 45-minute news conference this morning, Mario Ruiz Massieu said he's given the government evidence that the PRI's president and secretary-general (the second- and third-most powerful Mexican officials ) had blocked his investigation into the shooting of Jose Francisco Ruiz Massieu , Mexico's No. 2 official and a future presidential contender. He also said his boss, Attorney General Humberto Benitez Trevino, joined in the cover-up. Ruiz Massieu distributed a 97-page book he said contained "proof" of the alleged misdeeds.