US President Barack Obama has called for investigations both by Pakistan and the United States into the possibility that some people of the Pakistan government may have been involved in providing support structure for terrorist leader Osama bin Laden in Abbottabad. In his first interview after bin Laden's death, Obama told the '60 Minutes' show on 'CBS News' that it is not known whether there might have been some people in support of Bin laden, inside of Pakistan government or outside it, and that have to be investigated, more importantly, by the Pakistani government. Obama said, America thinks that there had to be some sort of support network for bin Laden inside of Pakistan, but don't know who or what that support network was. Obama's comments came as US President's top security advisor said that there was no evidence so far that the Pakistan Government knew about the al-Qaeda Chief's presence in the country.