It's settled

The commission interviewed over 1,200 people in 10 countries and reviewed over two and a half million pages of documents, including some closely guarded classified national security documents. The commission also relied heavily on the FBI's PENTTBOM investigation. Before it was released by the commission, the final public report was screened for any potentially classified information and edited as necessary.....

https://en.m.wikipedia.org/wiki/9/11_Commission_Report

Seems to me that is the sum total of the "proof" we have from Russia is Russia saying "We didn't do it."

One thing he was never formally indicted for it. Then you have the questionable Bin Laden video where he does admit. Early reports after 9/11 indicated the NSA heard "chatter" that Bin Laden was responsible.

Personally, I'm certain Bandar Bush was the point man for the attacks plus the CIA met with 2 of the hijackers before entering Florida (or maybe San Diego-- I'd have to look it up) and failed to give the FBI a heads up.

Prince and the '28 pages': Indirect 9/11 link to Saudi royal revealed

Washington (CNN)When the United States caught its first big al Qaeda operative, six months after the 9/11 terror attacks, it found a disturbing clue: phone numbers linked to the United States.

In an overnight raid, Pakistani forces captured Abu Zubaydah, allegedly a recruiter for the terror group and a member of Osama bin Laden's inner circle.

Now, 14 years after Zubaydah was apprehended, newly declassified information from a 2002 congressional report on the 9/11 attacks, dubbed the "28 pages," reveals an indirect link previously hidden from the American public between the alleged al Qaeda operative and a company associated with a key member of the Saudi royal family, former Saudi Ambassador to the United States Prince Bandar bin Sultan.

Ever since 19 men -- 15 of them Saudi nationals -- hijacked four airplanes and changed the course of American history, the possibility of official Saudi involvement has hung over the relationship between the two countries. While the alleged association with Bandar revealed in the newly declassified pages does not provide direct evidence the prince was complicit in the 9/11 attacks, it raises new questions about Saudi Arabia's involvement.

The connection to Bandar was made through Zubaydah's phone book, retrieved during the Pakistani raid in which he was taken. In it, the FBI found numbers linked to the United States, including an unlisted number for a company that managed Bandar's estate in Aspen, Colorado. An unlisted number was also found for a bodyguard who worked at the Saudi Embassy in Washington.

http://www.cnn.com/2016/08/05/politics/28-pages-saudi-prince-bandar-9-11/index.html