KUALA LUMPUR, May 15 — Tun Dr Mahathir Mohamad told Prime Minister Datuk Seri Anwar Ibrahim again today to substantiate claims the former had enriched himself and his family while in power. The former prime minister said Anwar has repeatedly failed to back up such claims when challenged to do so, but instead told Dr Mahathir to refute his allegations including by suing. Dr Mahathir said his assets were known from previous declarations while in office, and that he was already suing Anwar for...