Almost 15 years after the coordinated terrorist attacks launched by Islamist radicals in America on September 11, 2001, families of thousands of victims are still searching for answers as to who was behind this atrocious act.

Former Florida Senator Bob Graham believes that the key to unlocking who really engineered the 9/11 attacks lies in documents that have been kept secret by the American government: the redacted minutes of the congressional joint inquiry on intelligence before and after the incident.

Graham, who co-chaired the inquiry, is also convinced that Saudi Arabia's government is linked to the 9/11 attacks and continues to fund terrorist groups up to this day.

Interviewed on Wednesday by Yahoo News host Stephanie Sy on "Yahoo News Live," the former lawmaker emphasised the need to shed light on the documents to make public once and for all Saudi's alleged involvement in the attacks, and to give closure to the families of the victims.

"I think [they're] a smoking gun. I think the linkages are so multiple and strong and reinforcing that it's hard to come away from reading all this material and not feel that there was a support network and that support network came from Saudi Arabia," Graham said.

He added that opening these documents to public scrutiny can open the floodgates to more revelations about Saudi Arabia's supposed connections with terror groups.

"They will also open the path to other materials. There are thousands of pages of documents, which speak to the relationship between Saudi Arabia and the 19 hijackers," the ex-senator added.

He likewise emphasised the need to pass the proposed legislation allowing families of 9/11 victims to sue the Saudi Arabian government. He said doing so will be a "big victory" for Americans.

"It not only is going to open up the courts of justice to the families and the victims of 9/11. It also has the potential of exposing a tremendous amount of information relative to Saudi Arabia's involvement in 9/11," he said.

Graham also indicated that the U.S. government may very well release the secret 9/11 documents soon, after he met with Director of National Intelligence James Clapper.

"The general has been reviewing these pages closely for a year or more. He told us that before the end of this week, he would probably have his review completed. Then it goes to a panel that's made up of several agencies [FBI, the Department of State] who will look at the 28 pages for their issues of concern, and then it goes to the President for his determination as to whether to declassify these papers," Graham said.

Saudi Arabia has warned the Obama administration that it will sell off U.S. Treasury debt worth $750 billion if Congress passes a law clearing the way for 9/11 victims to sue the kingdom for its alleged role in aiding the hijackers, according to the New York Times.

Such sell-off would hurt the U.S. economy since it would prompt an increase in U.S. Treasury interest rates, raising borrowing costs for the American government, businesses and consumers and potentially triggering an economic downturn that could extend beyond U.S. shores.

Graham said failing to hold Saudi Arabia to account for its "complicity in the murder of 3,000 Americans" gave the kingdom "a sense of impunity that they can do anything they wanted to with no sanction, and now that impunity has expanded to their trying to lobby the highest levels of the White House and the Congress" to prevent a courtroom determination of Saudi Arabia's guilt.