UNITED NATIONS-On the eve of former Prime Minister Mohtarma Benazir Bhuttos birthday, the UN announced that its three-member commission established to look into her assassination will begin its mandated six-month work on July 1. But a statement read out by UN spokesperson said, 'the duty of determining the criminal responsibility of the perpetrators of the assassination remains with the Pakistani authorities. Asked why that determination has been left to the Pakistani authorities, Spokesperson Michelle Montas said the commission was not a tribunal. 'The Secretary-General has informed the Government of Pakistan, by letter to President Asif Ali Zardari, that the Commission of Inquiry into the facts and circumstances of the assassination of former Pakistani Prime Minister Mohtarma Benazir Bhutto will commence its six month mandate on 1 July 2009, she said in a statement read out at the regular noon briefing. The Commission, is headed by Chiles UN Ambassador Heraldo Muoz, and includes Marzuki Darusman of Indonesia; and Peter Fitzgerald of Ireland. 'In accordance with the agreed Terms of Reference, the Commissions mandate will be to inquire into the facts and circumstances of the assassination of former Prime Minister Benazir Bhutto, she said. The statement said the Commission will submit its report to the Secretary-General within six months of the commencement of its activities. The Secretary-General, she said, will share the report with the Pakistan Government and submit it to the Security Council for information. 'The Secretary-General notes that the anniversary of the birth of former Prime Minister Benazir Bhutto is on June 21, and is a reminder of the tragic loss suffered by her family and the Pakistani people. 'The United Nations is committed to assisting Pakistan by determining the facts and circumstances of her death, the statement added. Last weeks appointment of Fitzgerald, a former senior Irish police officer who had also worked on the Hariri Commission, completed the composition of the inquiry body. A six-member UN technical team for the commission has already paid a week-long trip to Pakistan to prepare the ground for the UN probe. The team was headed by Mark Quarterman, who had also worked on the Hariri Commission. The Pakistani govt had requested the UN to establish a commission to investigate Ms. Bhuttos killing. It has already paid 1.8 million dollars to the UN as seed money to cover its initial costs, and more countries are likely to contribute. Bhutto was assassinated in gunshot and suicide bombing attacks on Dec. 27, 2007 after addressing an election rally at a park in Rawalpindi.