The Official Account
Osama bin Laden was responsible  for the 9/11 attacks.
The Best Evidence
The FBI did not list 9/11  as one of the terrorist acts for which Osama bin Laden was wanted.
Also, although Secretary of State Colin Powell, British Prime Minister Tony Blair, and the 9/11 Commission promised  to provide evidence of Bin Laden’s responsibility for the 9/11 attacks, they also failed. 
References for General Point 1
- The 9/11 Commission Report, 2004
- Federal Bureau of Investigation, “Most Wanted Terrorists.”
- Ed Haas, “FBI says, ‘No Hard Evidence Connecting Bin Laden to 9/11’” Muckraker Report, June 6, 2006.
- Federal German Judge Dieter Deiseroth, in a December 2009 statement, stated that no independent court has verified the evidence against bin Laden. “Bush rejects Taliban offer to hand Bin Laden over,” Guardian, October 14, 2001. The Taliban said they would turn bin Laden over if the US provided evidence of his guilt.
“Taliban Met With U.S. Often: Talks centered on ways to hand over bin Laden,” Washington Post, October 29, 2001. The Taliban asked for evidence of bin Laden’s guilt but it was not forthcoming.
“The investigation and the evidence” (backup), BBC News, October 5, 2001. “There is no direct evidence in the public domain linking Osama Bin Laden to the 11 September attacks.”
- Powell: “Meet the Press,” NBC, September 23, 2001.
Blair: Tony Blair: Office of the Prime Minister, “Responsibility for the Terrorist Atrocities in the United States,” BBC News, October 4, 2001.
- Powell: “Remarks by the President, Secretary of the Treasury O’Neill and Secretary of State Powell on Executive Order,” White House, September 24, 2001.
Seymour M. Hersh, “What Went Wrong: The C.I.A. and the Failure of
American Intelligence,” New Yorker, October 1, 2001.
Blair: Tony Blair: Office of the Prime Minister, “Responsibility for the Terrorist Atrocities in the United States,” BBC News, October 4, 2001. The government’s document stated that it “does not purport to provide a prosecutable case against Osama Bin Laden in a court of law.”
The 9/11 Commission Report (2004). All statements of bin Laden’s responsibility were based on interrogations of KSM [Khalid Sheikh Mohammed], under torture. See The 9/11 Commission Report notes at Ch. 5, notes 1, 10, 11, 16, 32, 40, and 41.