UN investigators have completed the questioning of several Syrian officials over the assassination of former Lebanese prime minister Rafiq al-Hariri, Syrian and UN officials say. "The team has returned from Damascus. They are set to meet tomorrow to assess their work in Syria and consider the next step," Nejib Friji, UN spokesman in Beirut, said.In Damascus, a Syrian foreign ministry official said the UN team had ended its visit and called Syria's cooperation with the investigators a sign of Syria's willingness to help them "to unveil the perpetrators of this horrendous crime". Neither Friji nor the Syrian official commented on the questions raised during the meetings. Head of the UN team Detlev Mehlis also handed control of the crime scene back to Lebanese officials, Friji said, after foreign experts concluded their investigations. The spokesman said it was now up to the Lebanese authorities when to reopen the road where a large truck bomb killed al-Hariri and 20 other people on 14 February. Neither side has named the officials interviewed but Lebanese political sources have said the at least eight officials questioned include senior intelligence officers working in Lebanon at the time and their commanders in Syria.