JAKARTA, March 24 (Reuters) - A truth commission set up by Indonesia and East Timor will hold its second public hearing next week in an attempt to uncover the facts surrounding a bloody independence vote in East Timor in 1999. "This hearing is aimed first at knowing what exactly happened ... whether there was any human rights violation or not," Benjamin Mangkoedilaga, co-chairman of the Truth and Friendship Commission, told reporters on Saturday. "Second, of course, the questions will be asked on why the incidents occurred ...and to investigate who must take responsibility." Former president B.J. Habibie was expected to testify on Tuesday but the session will be closed. Another session will hear testimony from victims of three incidents of violence. The United Nations estimates about 1,000 East Timorese were slaughtered by pro-Jakarta militias when the former Portuguese colony overwhelmingly voted for independence. The militias, backed by elements in the Indonesian army, also destroyed most of East Timor's infrastructure. Mainly Catholic East Timor became fully independent in May 2002 after 2-1/2 years of U.N. administration that followed 24 years of brutal Indonesian occupation. Critics say the commission is toothless because it lacks the power to punish those found responsible for abuses. East Timor's second presidential election takes place on April 9 to find a replacement for independence hero Xanana Gusmao. Eight candidates are in the race in the country of less than 1 million which has been hit by occasional violence since May after the sacking of 600 mutinous soldiers from the western region.