BUENOS AIRES, July 21 — The Iranian government organized and carried out the bombing of a Jewish community center here eight years ago that killed 85 people and then paid Argentina's president at the time, Carlos Saúl Menem, $10 million to cover it up, a witness in the case has said in sealed testimony. A 100-page transcript of a secret deposition, provided to The New York Times by Argentine officials frustrated that the case remains unsolved, supports long-held suspicions of Iranian involvement and adds to the questions surrounding the conduct of an inquiry that has been rife with irregularities from...