It is one of the world's biggest conspiracy theories – that the west was involved in plotting, organising, and even carrying out the 9/11 terror atrocities. One longstanding view is the towers would not have collapsed in the way they did if they were hit by aircraft. Some claim there must have been a controlled detonation" at ground level for the Twin Towers to fall in on themselves as they did. One key part of their argument is the collapse of a third smaller tower, called Building 7, at the World Trade Centre complex, several hours after the huge skyscrapers fell. Now, the University of Alaska is sponsoring a full investigation into claims that World Trade Center Building 7 was brought down by a controlled demolition during the 9/11 attacks. Dr J Leroy Hulsey, chair of the University of Alaska Fairbanks' (UAF) Civil and Environmental Engineering Department, has partnered with architects and engineers linked to campaign group 9/11 Truth to evaluate the causes of its collapse. WTC7 was not hit by a plane. However, it collapsed at 5:20 p.m. According to the National Institute of Standards and Technology (NIST), the official cause for the collapse was office fires. A growing number of family members, activists, architects and engineers question the official theory for collapse and are seeking a new investigation into WTC7. Dr Hulsey ... said: "NIST says the building fell down due to office fires. Our investigation will evaluate the probability that this was the cause of the collapse."