Who could have committed the crimes of September 11, 2001? Answering that question requires understanding the details of 1) what happened that should not have happened and 2) what did not happen that should have happened. Additionally, it requires asking specific, well-formulated questions and seeking answers that are evidence-based to assess potential suspects in terms of means, motive, and opportunity.

In my book Another Nineteen: Investigating Legitimate 9/11 Suspects, a case is made for the investigation of nineteen people who were in position to do everything that was needed to affect the crimes. These legitimate suspects can be compared to the nineteen young Arabs who were accused of the crimes yet who did not have the means or opportunity to accomplish most of what happened that day.

The following seven questions should be asked when considering suspects. For each question, my nominees are described.

Who could have prevented U.S. intelligence agencies from tracking down and stopping the alleged hijackers before 9/11? Louis Freeh was Director of the FBI for the nine years leading up to 9/11. Under Freeh’s leadership, the FBI failed miserably at preventing terrorism when preventing terrorism was the FBI’s primary goal. During this time the actions of FBI management suggest that it was facilitating and covering-up acts of terrorism. After 9/11, Freeh went on to become the personal attorney for Saudi Arabian ambassador Prince Bandar and a director for a company linked to 9/11 insider trading.

As Director of the Central Intelligence Agency (DCI) from 1997 to 2004, George Tenet led an agency that botched and bungled its duties related to counterterrorism. The evidence suggests that, as with Louis Freeh and the FBI, at least some of those failures were intentional. Tenet had developed secret paths of communication with Saudi authorities and he appears to have disrupted plans to capture or investigate al Qaeda suspects.

Richard Clarke was appointed U.S. “Counterterrorism Czar” by President George H.W. Bush in1992 and he held that position until after the 9/11 attacks. Clarke was also a member of the highly secret Continuity of Government planning group along with Dick Cheney and Donald Rumsfeld and he implemented that secret plan for the first time on 9/11. He was a personal representative of the government of the United Arab Emirates (UAE), a country that financed terrorism and had many ties to 9/11. Clarke predicted terrorist attacks on Washington and New York and, through tipping off his friends in the UAE, was behind the failure of two CIA attempts to kill or capture Osama Bin Laden. On 9/11, he led the secure White House videoconference that failed to respond to the attacks.

Richard Armitage was a special operations soldier, long-time covert operative, and a member of the Project for a New American Century (PNAC). On 9/11, Armitage was Deputy Secretary of State and, in this role, he implemented an express approval program that provided visas to the alleged 9/11 hijackers. On 9/11, he was involved in the secure videoconference run by Richard Clarke that failed to respond to the hijacked airliners.

Who could have disabled the systems in place to prevent hijackings that should have been effective? On 9/11, General Michael Canavan was in the role of hijack coordinator for the Federal Aviation Administration (FAA) but he was mysteriously missing that morning. Canavan’s role was most responsible for communications between the FAA and the military and his absence was critical to the failure of air defenses. Having only started as FAA’s hijack coordinator just months earlier, Canavan left the position in October 2001. According to an FAA intelligence employee, Canavan started his job by running training exercises that were “pretty damn close to the 9/11 plot.”

Duane Andrews, a long time protégé of Dick Cheney, was a leading expert on the defense systems that failed on 9/11. At the time, he led the company Science Applications International (SAIC) that created the national databases to track and identify terrorists, supplied U.S. airports with terrorism screening equipment, predicted and investigated terrorist attacks against U.S. infrastructure including national defense networks and the WTC, helped create the official account for what happened at the WTC both in 1993 and after 9/11, was a leader in research on thermitic materials like those found in the WTC dust, led the robotics team that scoured the pile at Ground Zero using equipment capable of eliminating explosives, and provided the information to capture the alleged mastermind of the attacks, Khalid Sheik Mohammed.

Benedict Sliney was the FAA’s Command Center national operations manager on 9/11. It was his first day in the job, having just left a lucrative law career defending Wall Street financiers. Despite his lack of experience, his FAA superiors deferred to him as the attacks proceeded and allowed him to take charge of the response to the hijacked airliners. Sliney’s failure to respond effectively on the day of the attacks, allegedly not even knowing how to respond, contributed significantly to the failure of the national air defenses.

Who could have disabled the U.S. chain of command that should have immediately responded to the attacks but did not? Secretary of Defense Donald Rumsfeld was in charge of U.S. defenses on 9/11. After the Pentagon was hit, Rumsfeld wandered out to the parking lot for approximately 30 minutes. His presence there showed that he was not concerned about other planes that were reported as hijacked, as if he knew what to expect. Rumsfeld did not concern himself with the work of his direct subordinate, NORAD Commander Ralph Eberhart, and he did not do his job to ensure the nation’s air defenses. Rumsfeld and his Defense department later failed to cooperate with 9/11 investigations.

Vice President Dick Cheney was in charge at the White House on 9/11 and is known to have been the primary decision maker that day. In the Presidential Emergency Operations Center, Cheney gave instructions that appear to have directed a stand down of air defenses as well as an order to shoot down United Flight 93. Cheney later worked to prevent any investigation into 9/11 and led a campaign of lies to start the Iraq War.

Who could have disabled the U.S. national air defenses that should have responded effectively and intercepted some, if not all, of the hijacked aircraft? Ralph Eberhart, the commander of NORAD on 9/11, sponsored the highly coincidental military exercises (i.e. war games) that obstructed the military response. Twelve hours before the attacks, Eberhart apparently ordered the defense readiness alert system Infocon to its least protective level, making it easier to hack or compromise the defense computer networks. Failing in his duties to protect the nation while giving orders that further prevented response, Eberhart later lied to Congress about the military’s knowledge of the hijackings.

As a special agent in charge for the Secret Service, Carl Truscott supervised all protective matters relating to the president, the first family, and the White House. The response of the Secret Service to the 9/11 attacks suggests foreknowledge of the events because the agency failed to protect the president from the obvious danger posed by terrorists. Combined with the failure of the Secret Service to follow-up on offers of air support from Andrews Air Force Base, this led to the suspicion that the agency was complicit in the attacks.

Who could have caused three WTC skyscrapers to fall through the path of what should have been the most resistance? Brian Michael Jenkins, as deputy chairman of Crisis Management for Kroll Associates, played a leading role in planning for terrorist events at the WTC, including having reviewed the possibility of airliner crashes into the towers. A special operations soldier and long-time right-wing political advisor, Jenkins had been accused of implementing a “terror war” in Central America during the 1980s.

Wirt Walker was named a 9/11 insider trading suspect in previously classified 9/11 Commission documents. Walker’s company Stratesec provided security services for the WTC, United Airlines (which owned two of the planes hijacked on 9/11), and Dulles Airport (where American Airlines Flight 77 took off that day). Stratesec held its annual meetings in offices leased by Saudi Arabia and Walker also ran an aviation company in Oklahoma at an airport that was associated with the alleged hijackers.

Barry McDaniel was the chief operating officer of Stratesec. McDaniel was in charge of WTC security in terms of what he called a completion contract, to provide services up to the day the buildings fell down. He is also an Iran-Contra suspect and previously worked for companies that conducted covert operations, like Sears World Trade and The Vinnell Corporation. After 9/11, McDaniel went on to start a business with Dick Cheney’s former business partner, Bruce Bradley.

Rudy Giuliani was Mayor of New York City on 9/11. He and his staff had foreknowledge that the WTC Towers would fall when no one could have predicted such a thing. Giuliani was also responsible for the destruction of critical WTC evidence at Ground Zero. In a crime that continues to take lives, he told people in the area that the air was safe to breathe, when it was not, in order to speed the removal of evidence.

L. Paul Bremer’s career with the State Department and as managing director of Kissinger Associates led to him becoming, like Jenkins, one of few leading experts on terrorism before 9/11. On the day of 9/11, Bremer had an office in the South Tower of the WTC and was working for Marsh & McLennan, a company that occupied all the impact floors in the North Tower. Also associated with a company that had patented a thermite demolition device, Bremer was one of the first people to provide the official account for what happened on television that morning.

Who could have coordinated an attack against the Pentagon that struck the exact spot that had just been renovated while allowing all Pentagon leadership to escape unharmed? Paul Wolfowitz was Deputy Secretary of Defense on 9/11. Along with Armitage, Cheney, and Rumsfeld, Wolfowitz was a leader of the organization PNAC that, one year before 9/11, had called for a transformational event “like a New Pearl Harbor” to reinvigorate U.S. military spending. In the eight months leading up to 9/11, Wolfowitz led the Pentagon building project that renovated the exact spot where Flight 77 was reported to have impacted the building.

Peter Janson was the chief officer of AMEC Construction, the company that performed the renovation work on the Pentagon building in the exact spot where it was hit on 9/11. AMEC was also hired to clean-up the debris at both the Pentagon and the WTC immediately after the attacks. A long-time business associate of Donald Rumsfeld, Janson went on to benefit from the War on Terror as a director of an oil and gas transport company.

Who could have ensured that no effective investigation was conducted and that no one was held accountable? Porter Goss was a CIA operative who, after 9/11, became DCI. On the day of 9/11, Goss was meeting with Pakistani secret service (ISI) General Mahmud Ahmed as the first plane struck the WTC. He later helped cover-up the crimes through his leadership of the Congressional Joint Inquiry into 9/11. As DCI in 2004, Goss took actions to ensure that no one in the intelligence community was held responsible for 9/11.

Robert Mueller, although not named as a suspect in my book, was a leader of the 9/11 cover-up in his role as director of the FBI, a position he took one week before the 9/11 attacks. Mueller had a history of covering-up government crimes including FBI collusion with organize crime, the 1988 bombing of Pan Am 103, and the CIA terrorist financing network known as BCCI. That made him the perfect guy to lead the FBI investigation into 9/11.

It should be obvious that the 19 young Arab suspects accused of the crimes could not have accomplished any of the things required to pull off the 9/11 crimes, as described in these seven questions that need to be answered. In fact, the evidence indicates they could not even fly small aircraft. On the other hand, the suspects noted above not only had the means, motive, and opportunity to carry out the crimes, many of them were long-time associates known to have engaged in covert operations or cover-ups. Anyone who is objective in an analysis of 9/11 suspects knows which of these groups should be investigated first.