 In 2002, the National Institute of Standards and Technology (NIST) began a general investigation into the collapse of the World Trade Center but soon made a decision to focus first on the collapse of the Twin Towers.A draft version of its final report on the collapse of 7 WTC was released in August 2008.The agency has blamed the slowness of this investigation on the complexity of the computer model it used, which simulated the collapse from the moment it begins all the way to the ground; and NIST says the time taken on the investigation into 7 WTC is comparable to the time taken to investigate an aircraft crash.