Only a blind denialist (or perhaps a paid one) could so easily dismiss such a group as this (and this is only from the first link in 2Serious's post):
|Dr. Ellsberg is one of many signers of a petition to reinvestigate 9/11.  Best known for leaking the Pentagon Papers to the New York Times in 1971, Dr. Ellsberg is a former U.S. State Department envoy to Viet Nam and Special Assistant to the Assistant Secretary of Defense.
Another State Department critic of the official account of 9/11 is Col. Ann Wright, who said in a 2007 interview with Richard Greene on the Air America Radio Network, “It's incredible some of these things that still are unanswered. The 9/11 Report -- that was totally inadequate. I mean the questions that anybody has after reading that.” 
Col. Wright is one of three U.S. State Department officials to publicly resign in direct protest of the invasion of Iraq in March, 2003. She joined the Foreign Service in 1987 and served for 16 years as a U.S. Diplomat, including assignments as Deputy Chief of Mission of U.S. Embassies in Sierra Leone, Micronesia and Afghanistan. She helped reopen the U.S. Embassy in Kabul in December, 2001. She also served for 13 years on active duty and 16 additional years on reserve duty with the U.S. Army.
She continued in her interview with Greene: “How could our national intelligence and defense operations be so inept that they could not communicate; that they could not scramble jets; that they could not take defensive action? And I totally agree, I always thought the Pentagon had all sorts of air defense equipment around it; that they could take out anything that was coming at it. And for a plane to be able to just fly low right over Washington and slam into that thing is just -- I mean, you still just shake your head. How in the world could that happen?”
|Another former career Foreign Service Officer who questions the official account of 9/11 is Michael Springmann. He is also one of many signers of the petition to reinvestigate 9/11.
In a speech at the National Press Club, Mr. Springmann said, “I used to be in charge of the visa section at the CIA's Consulate in Jeddah. ... There for a year and a half I issued visas to terrorists recruited by the CIA and its asset Osama Bin Laden. ... Fifteen of the nineteen people who allegedly flew airplanes into buildings in the United States got their visas from the same CIA Consulate at Jeddah.” 
|During his more than 20 years of U.S. government service, Mr. Springmann worked at both the State Department and the Foreign Commercial Service of the U.S. Department of Commerce. Among his many assignments, Mr. Springman served as Consular Officer in Jeddah, Saudi Arabia, where he supervised the issuance of visas.
In a later interview with the BBC, Mr. Springmann said, “In Saudi Arabia I was repeatedly ordered by high level State Dept officials to issue visas to unqualified applicants. These were, essentially, people who had no ties either to Saudi Arabia or to their own country. I complained bitterly at the time there. I returned to the US, I complained to the State Dept here, to the General Accounting Office, to the Bureau of Diplomatic Security and to the Inspector General's office. I was met with silence. ... What I was protesting was, in reality, an effort to bring recruits, rounded up by Osama Bin Laden, to the US for terrorist training by the CIA. They would then be returned to Afghanistan to fight against the then-Soviets.” 
Another State Department veteran publicly questioning the official account of 9/11 is former career Foreign Service Officer, George Kenney, who served as Yugoslav desk officer at the State Department headquarters in Washington, D.C. He resigned his commission in 1991 over U.S. policy towards the Yugoslav conflict. He then served as consultant in residence at the Carnegie Endowment for International Peace. Currently he’s a consultant and commentator on foreign affairs and current events.
In a commentary after a 2007 interview of David Ray Griffin, PhD, Mr. Kenney said, “We should strive to clearly separate what we know from things we don't. Thus, we have a reasonably high level of confidence that the Establishment conspiracy narrative is absurd. The World Trade Center structures came down through controlled demolition. Flight 93 was shot down over rural Pennsylvania. And whatever it was that hit the Pentagon could not have been Flight 77. Further, whatever his peripheral involvement, the planning and implementation of 9/11 did not originate with Osama bin Laden.” 
|Michael Mennard, PhD, is another U.S. State Department veteran who questions the official account of 9/11 and calls for a new investigation. Among his assignments as a career Foreign Service Officer, Dr. Mennard served as Regional Public Affairs Officer in India.
In a statement to this author, Dr. Mennard wrote, “I am concerned about the numerous inconsistencies in the official account of 9/11. I support a new investigation regarding the tragic events of that day, the events leading up to it, and subsequent efforts to ignore the whole matter.”
|Shortly after the release of the 9/11 Commission Report, a group of over 100 prominent Americans signed a petition  urging Congress to immediately reinvestigate 9/11. In addition to six former CIA officials,  the signers included Daniel Ellsberg, Melvin Goodman, Fred Burks, Michael Springman (all mentioned above), and Edward Peck.
Edward Peck served as Deputy Coordinator, Covert Intelligence Programs at the State Department. He later served as Deputy Director of the White House Task Force on Terrorism under President Ronald Reagan. Mr. Peck, a 32-year veteran of the U.S. Foreign Service, also served as U.S. Ambassador and Chief of Mission in Iraq (1977 - 1980).
|The petition stated, in part, “We want truthful answers to questions such as:
1. Why were standard operating procedures for dealing with hijacked airliners not followed that day?
2. Why were the extensive missile batteries and air defenses reportedly deployed around the Pentagon not activated during the attack?
3. Why did the Secret Service allow Bush to complete his elementary school visit, apparently unconcerned about his safety or that of the schoolchildren?
4. Why hasn't a single person been fired, penalized, or reprimanded for the gross incompetence we witnessed that day?
5. Why haven't authorities in the U.S. and abroad published the results of multiple investigations into trading that strongly suggested foreknowledge of specific details of the 9/11 attacks, resulting in tens of millions of dollars of traceable gains?”
These questions and many others still remain unanswered three years after the petition was submitted and six years after the terrible events of 9/11. As the statements of these eight U.S. State Department veterans show, the need for a new thorough and independent investigation of 9/11 is not a matter of partisan politics, nor the demand of irresponsible, deranged, or disloyal Americans. It is instead a matter of the utmost importance for America’s security and the future of the entire world.
Statements questioning the official account of 9/11 and calls for a new investigation by more than 800 credible individuals can be found at http://PatriotsQuestion911.com
Additional information about prominent skeptics of the official account of 9/11 can be found in the author's other articles on this subject, listed below.
Dec. 13, 2007 - Seven Senior Federal Engineers and Scientists Call for New 9/11 Investigation - Official Account of 9/11: “Impossible”, “A Bunch of Hogwash”, “Fatally Flawed” featured statements by:
Sept. 5, 2007 - U.S. Navy 'Top Gun' Pilot Questions 9/11, featured the statement of Commander Ralph Kolstad, U.S. Navy ‘Top Gun’ pilot.
Sept. 4, 2007 - Former Congressional Office of Technology Assessment Senior Staff Member Calls for New Investigation of 9/11 featured the statement of Joel S. Hirschhorn, Ph.D., who served for 12 years as a Senior Staff Member of the Congressional Office of Technology Assessment and later as Director of Environment, Energy and Natural Resources for the National Governors Association.
Aug. 27, 2007 - National Academy of Sciences Member Calls for New 9/11 Investigation featured the statement of Lynn Margulis, Ph.D., world renowned scientist.
Aug. 21, 2007 - Former Chief of NIST's Fire Science Division Calls for Independent Review of World Trade Center Investigation featured the statement of James Quintiere, Ph.D., one of the world's leading fire science researchers.
July 16, 2007 - Former California Seismic Safety Commissioner Endorses 9/11 Truth Movement featured the statement of J. Marx Ayres, former member of the National Institute of Sciences Building Safety Council and former member of the California Seismic Safety Commission.