The international tribunal investigating the 2005 killing of a former Lebanese prime minister, Rafik Hariri, requested Wednesday that Hezbollah turn over evidence that the militant group says implicates Israel in the assassination. On Monday, Hassan Nasrallah, Hezbollah’s leader, presented what he said were videotaped confessions, maps and previously unreleased Israeli spy videos that he said pointed to Israel as the culprit in Mr. Hariri’s killing. Mr. Nasrallah has said in earlier speeches that the tribunal was planning to indict Hezbollah members in the killing, and he has accused the tribunal of distorting its findings to suit a political agenda.