A United Nations investigation into the assassination of the former Lebanese prime minister is making progress, according the chief prosecutor in charge. In a briefing before the Security Council Friday, Serge Brammertz, chief prosecutor on the investigation into the murder of Rafiq Hariri said his team had made some preliminary conclusions and now has a better understanding of how the assassination was planned. Hariri and 22 others were killed in a February 2005 car bomb explosion in Beirut. The Commission has reached preliminary conclusions about a number of issues that were previously unclear, Brammertz told council members. He discounted the possibility that two explosions occurred, saying witness testimony of two separate sounds can be explained scientifically. Brammertz acknowledged that violence in Lebanon had forced the investigative team to relocate temporarily, but said the Commission has made progress in its investigation and in the expanded technical assistance it provides to the Lebanese authorities in the investigations of certain other crimes. The team is assisting Lebanese authorities with investigations into 14 attacks, including bombings, assassinations, and attempted assassinations carried out in Lebanon since October 2004. The investigators are looking into possible links between the Hariri murder and the other crimes. The attack that killed Hariri involved the use of 1,800 kg of explosives, not 1,200 kg, as previously suggested, Brammertz reported. Investigators have also found DNA evidence at the crime scene suggesting that a suicide bomber -- a man in his early 20s detonated the bomb. His DNA is being compared with existing databases in several countries, he said. Brammertz told council members that he had asked for cooperation from a number of countries in the investigation, including requests for assistance, witness protection and recruiting personnel for help in the investigation. The Commission is satisfied with the progress made so far in the investigations and will continue to attain the best possible results throughout the next reporting period and until the end of the current mandate in June 2007, Brammertz said.